CVE-2026-42768

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was explicitly disabled.

The implicit rejection mechanism always returns a plaintext value, the symmetric key. This result is deterministic for the ciphertext and the private key. The length of the decryption result can happen to match the length of the key of the symmetric cipher that was used for the content encryption. When a certificate is not provided, the last RecipientInfo producing a key that looks valid will be used. It may cause getting garbage content on decryption. As a proper way to deal with this a recipient certificate has to be provided to identify the particular RecipientInfo for decryption.

The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary.

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output. Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key. The attack is possible in 2 variants. 1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success. An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available. That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it. 2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted. An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle. We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity. To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was explicitly disabled. The implicit rejection mechanism always returns a plaintext value, the symmetric key. This result is deterministic for the ciphertext and the private key. The length of the decryption result can happen to match the length of the key of the symmetric cipher that was used for the content encryption. When a certificate is not provided, the last RecipientInfo producing a key that looks valid will be used. It may cause getting garbage content on decryption. As a proper way to deal with this a recipient certificate has to be provided to identify the particular RecipientInfo for decryption. The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary.

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was explicitly disabled.

The implicit rejection mechanism always returns a plaintext value, the symmetric key. This result is deterministic for the ciphertext and the private key. The length of the decryption result can happen to match the length of the key of the symmetric cipher that was used for the content encryption. When a certificate is not provided, the last RecipientInfo producing a key that looks valid will be used. It may cause getting garbage content on decryption. As a proper way to deal with this a recipient certificate has to be provided to identify the particular RecipientInfo for decryption.

The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary.

EDK II is a modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications.

Security Fix(es):

Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as OPTIONAL in the ASN.1 specification and may therefore be absent in specially crafted inputs. During the password-based CMS decryption the OpenSSL CMS implementation dereferences this field without first checking whether it was present.

An attacker who supplies such a CMS message to an application performing password-based CMS decryption can trigger an application crash, leading to a Denial of Service.

Applications that process password-encrypted CMS messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42766)

Issue summary: An attacker-controlled CMP (Certificate Management Protocol) server could trigger a NULL pointer dereference in a CMP client application.

Impact summary: A NULL pointer dereference causes a crash of the application and a Denial of Service.

An attacker controlling a CMP server (or acting as a man-in-the-middle) could craft a CMP response containing a CRMF (Certificate Request Message Format) CertRepMessage with an EncryptedValue structure where the symmAlg field has an algorithm OID but no parameters field. When the OpenSSL CMP client processes this response, the NULL dereference occurs, causing a crash of the CMP client.

Applications that process untrusted CMP/CRMF messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42767)

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was…

EDK II is a modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications.

Security Fix(es):

Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as OPTIONAL in the ASN.1 specification and may therefore be absent in specially crafted inputs. During the password-based CMS decryption the OpenSSL CMS implementation dereferences this field without first checking whether it was present.

An attacker who supplies such a CMS message to an application performing password-based CMS decryption can trigger an application crash, leading to a Denial of Service.

Applications that process password-encrypted CMS messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42766)

Issue summary: An attacker-controlled CMP (Certificate Management Protocol) server could trigger a NULL pointer dereference in a CMP client application.

Impact summary: A NULL pointer dereference causes a crash of the application and a Denial of Service.

An attacker controlling a CMP server (or acting as a man-in-the-middle) could craft a CMP response containing a CRMF (Certificate Request Message Format) CertRepMessage with an EncryptedValue structure where the symmAlg field has an algorithm OID but no parameters field. When the OpenSSL CMP client processes this response, the NULL dereference occurs, causing a crash of the CMP client.

Applications that process untrusted CMP/CRMF messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42767)

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was…

EDK II is a modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications.

Security Fix(es):

Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as OPTIONAL in the ASN.1 specification and may therefore be absent in specially crafted inputs. During the password-based CMS decryption the OpenSSL CMS implementation dereferences this field without first checking whether it was present.

An attacker who supplies such a CMS message to an application performing password-based CMS decryption can trigger an application crash, leading to a Denial of Service.

Applications that process password-encrypted CMS messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42766)

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was explicitly disabled.

The implicit rejection mechanism always returns a plaintext value, the symmetric key. This result is deterministic for the ciphertext and the private key. The length of the decryption result can happen to match the length of the key of the symmetric cipher that was used for the content encryption. When a certificate is not provided, the last RecipientInfo producing a key that looks valid will be used. It may cause getting garbage content on decryption. As a proper way to deal with this a recipient certificate has to be provided to identify the particular RecipientInfo for decryption.

The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary.(CVE-2026-42768)

EDK II is a modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications.

Security Fix(es):

Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as OPTIONAL in the ASN.1 specification and may therefore be absent in specially crafted inputs. During the password-based CMS decryption the OpenSSL CMS implementation dereferences this field without first checking whether it was present.

An attacker who supplies such a CMS message to an application performing password-based CMS decryption can trigger an application crash, leading to a Denial of Service.

Applications that process password-encrypted CMS messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42766)

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was explicitly disabled.

The implicit rejection mechanism always returns a plaintext value, the symmetric key. This result is deterministic for the ciphertext and the private key. The length of the decryption result can happen to match the length of the key of the symmetric cipher that was used for the content encryption. When a certificate is not provided, the last RecipientInfo producing a key that looks valid will be used. It may cause getting garbage content on decryption. As a proper way to deal with this a recipient certificate has to be provided to identify the particular RecipientInfo for decryption.

The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary.(CVE-2026-42768)

EDK II is a modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications.

Security Fix(es):

Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as OPTIONAL in the ASN.1 specification and may therefore be absent in specially crafted inputs. During the password-based CMS decryption the OpenSSL CMS implementation dereferences this field without first checking whether it was present.

An attacker who supplies such a CMS message to an application performing password-based CMS decryption can trigger an application crash, leading to a Denial of Service.

Applications that process password-encrypted CMS messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42766)

Issue summary: An attacker-controlled CMP (Certificate Management Protocol) server could trigger a NULL pointer dereference in a CMP client application.

Impact summary: A NULL pointer dereference causes a crash of the application and a Denial of Service.

An attacker controlling a CMP server (or acting as a man-in-the-middle) could craft a CMP response containing a CRMF (Certificate Request Message Format) CertRepMessage with an EncryptedValue structure where the symmAlg field has an algorithm OID but no parameters field. When the OpenSSL CMP client processes this response, the NULL dereference occurs, causing a crash of the CMP client.

Applications that process untrusted CMP/CRMF messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-42767)

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was…

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols, as well as a full-strength general-purpose cryptography library.

Security Fix(es):

• openssl: OpenSSL: Heap buffer overflow due to signed integer overflow in Unicode output sizing (CVE-2026-7383)

• openssl: OpenSSL: Denial of Service due to heap out-of-bounds read in CMS password-based decryption (CVE-2026-9076)

• openssl: OpenSSL: Heap buffer over-read in ASN.1 decoding can lead to denial of service or information disclosure. (CVE-2026-34180)

• openssl: PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys (CVE-2026-34181)

• openssl: CMS AuthEnvelopedData Processing May Accept Forged Messages (CVE-2026-34182)

• openssl: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (CVE-2026-34183)

• openssl: NULL pointer dereference in QUIC server initial packet handling (CVE-2026-42764)

• openssl: Possible NULL Dereference in Password-Based CMS Decryption (CVE-2026-42766)

• openssl: NULL Pointer Dereference in CRMF EncryptedValue Decryption (CVE-2026-42767)

• openssl: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (CVE-2026-42768)

• openssl: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (CVE-2026-42769)

• openssl: FFC-DH Peer Validation Uses Attacker-Supplied q (CVE-2026-42770)

• openssl: AES-OCB IV Ignored on EVP_Cipher() Path (CVE-2026-45445)

• openssl: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (CVE-2026-45446)

• openssl: Heap Use-After-Free in OpenSSL PKCS7_verify() (CVE-2026-45447)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols, as well as a full-strength general-purpose cryptography library.

Security Fix(es):

• openssl: OpenSSL: Heap buffer overflow due to signed integer overflow in Unicode output sizing (CVE-2026-7383)

• openssl: OpenSSL: Denial of Service due to heap out-of-bounds read in CMS password-based decryption (CVE-2026-9076)

• openssl: OpenSSL: Heap buffer over-read in ASN.1 decoding can lead to denial of service or information disclosure. (CVE-2026-34180)

• openssl: PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys (CVE-2026-34181)

• openssl: CMS AuthEnvelopedData Processing May Accept Forged Messages (CVE-2026-34182)

• openssl: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (CVE-2026-34183)

• openssl: NULL pointer dereference in QUIC server initial packet handling (CVE-2026-42764)

• openssl: Possible NULL Dereference in Password-Based CMS Decryption (CVE-2026-42766)

• openssl: NULL Pointer Dereference in CRMF EncryptedValue Decryption (CVE-2026-42767)

• openssl: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (CVE-2026-42768)

• openssl: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (CVE-2026-42769)

• openssl: FFC-DH Peer Validation Uses Attacker-Supplied q (CVE-2026-42770)

• openssl: AES-OCB IV Ignored on EVP_Cipher() Path (CVE-2026-45445)

• openssl: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (CVE-2026-45446)

• openssl: Heap Use-After-Free in OpenSSL PKCS7_verify() (CVE-2026-45447)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output. Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key. The attack is possible in 2 variants. 1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success. An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available. That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it. 2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted. An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle. We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity. To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was explicitly disabled. The implicit rejection mechanism always returns a plaintext value, the symmetric key. This result is deterministic for the ciphertext and the private key. The length of the decryption result can happen to match the length of the key of the symmetric cipher that was used for the content encryption. When a certificate is not provided, the last RecipientInfo producing a key that looks valid will be used. It may cause getting garbage content on decryption. As a proper way to deal with this a recipient certificate has to be provided to identify the particular RecipientInfo for decryption. The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary.

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols, as well as a full-strength general-purpose cryptography library.

Security Fix(es):

• openssl: OpenSSL: Heap buffer overflow due to signed integer overflow in Unicode output sizing (CVE-2026-7383)
• openssl: OpenSSL: Denial of Service due to heap out-of-bounds read in CMS password-based decryption (CVE-2026-9076)
• openssl: OpenSSL: Heap buffer over-read in ASN.1 decoding can lead to denial of service or information disclosure. (CVE-2026-34180)
• openssl: PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys (CVE-2026-34181)
• openssl: CMS AuthEnvelopedData Processing May Accept Forged Messages (CVE-2026-34182)
• openssl: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (CVE-2026-34183)
• openssl: NULL pointer dereference in QUIC server initial packet handling (CVE-2026-42764)
• openssl: Possible NULL Dereference in Password-Based CMS Decryption (CVE-2026-42766)
• openssl: NULL Pointer Dereference in CRMF EncryptedValue Decryption (CVE-2026-42767)
• openssl: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (CVE-2026-42768)
• openssl: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (CVE-2026-42769)
• openssl: FFC-DH Peer Validation Uses Attacker-Supplied q (CVE-2026-42770)
• openssl: AES-OCB IV Ignored on EVP_Cipher() Path (CVE-2026-45445)
• openssl: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (CVE-2026-45446)
• openssl: Heap Use-After-Free in OpenSSL PKCS7_verify() (CVE-2026-45447)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols, as well as a full-strength general-purpose cryptography library.

Security Fix(es):

• openssl: OpenSSL: Heap buffer overflow due to signed integer overflow in Unicode output sizing (CVE-2026-7383)
• openssl: OpenSSL: Denial of Service due to heap out-of-bounds read in CMS password-based decryption (CVE-2026-9076)
• openssl: OpenSSL: Heap buffer over-read in ASN.1 decoding can lead to denial of service or information disclosure. (CVE-2026-34180)
• openssl: PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys (CVE-2026-34181)
• openssl: CMS AuthEnvelopedData Processing May Accept Forged Messages (CVE-2026-34182)
• openssl: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (CVE-2026-34183)
• openssl: NULL pointer dereference in QUIC server initial packet handling (CVE-2026-42764)
• openssl: Possible NULL Dereference in Password-Based CMS Decryption (CVE-2026-42766)
• openssl: NULL Pointer Dereference in CRMF EncryptedValue Decryption (CVE-2026-42767)
• openssl: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (CVE-2026-42768)
• openssl: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (CVE-2026-42769)
• openssl: FFC-DH Peer Validation Uses Attacker-Supplied q (CVE-2026-42770)
• openssl: AES-OCB IV Ignored on EVP_Cipher() Path (CVE-2026-45445)
• openssl: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (CVE-2026-45446)
• openssl: Heap Use-After-Free in OpenSSL PKCS7_verify() (CVE-2026-45447)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.

Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim's vulnerable application as a way to decrypt or sign messages with the victim's private RSA key.

The attack is possible in 2 variants.

1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.

An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim's public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.

That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO '98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim's key or forges any PKCS#1 v1.5 signature under it.

2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.

An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.

We are not aware of any applications that provide a remote attacker an opportunity to mount an attack described in these scenarios. We consider the existence of such application very unlikely, and for this reason this CVE has been evaluated as Low severity.

To avoid these attacks, when RSA PKCS#1 v1.5 Key Transport is in use, the invoked EVP_PKEY_decrypt() will use the implicit rejection mechanism described in draft-irtf-cfrg-rsa-guidance. In previous OpenSSL releases the implicit rejection was explicitly disabled.

The implicit rejection mechanism always returns a plaintext value, the symmetric key. This result is deterministic for the ciphertext and the private key. The length of the decryption result can happen to match the length of the key of the symmetric cipher that was used for the content encryption. When a certificate is not provided, the last RecipientInfo producing a key that looks valid will be used. It may cause getting garbage content on decryption. As a proper way to deal with this a recipient certificate has to be provided to identify the particular RecipientInfo for decryption.

The FIPS modules in 4.0, 3.6, 3.5, and 3.4 are not affected by this issue, as CMS and S/MIME processing happens outside the OpenSSL FIPS module boundary.

• CVE-2026-34180: fix heap buffer over-read in ASN.1 content parsing caused by truncating a long content length to int
• CVE-2026-7383: fix heap buffer overflow in ASN1_mbstring_ncopy() caused by signed integer overflow when computing the output length
• CVE-2026-42766: fix NULL pointer dereference when keyDerivationAlgorithm is absent in CMS PasswordRecipientInfo
• CVE-2026-9076: fix out-of-bounds read in kek_unwrap_key() check-byte validation for KEK ciphers with a block size below 4 octets
• CVE-2026-42768: enforce implicit rejection for CMS and PKCS#7 RSA PKCS#1 v1.5 decryption

• CVE-2026-34180: fix heap buffer over-read in ASN.1 content parsing caused by truncating a long content length to int
• CVE-2026-7383: fix heap buffer overflow in ASN1_mbstring_ncopy() caused by signed integer overflow when computing the output length
• CVE-2026-42766: fix NULL pointer dereference when keyDerivationAlgorithm is absent in CMS PasswordRecipientInfo
• CVE-2026-9076: fix out-of-bounds read in kek_unwrap_key() check-byte validation for KEK ciphers with a block size below 4 octets
• CVE-2026-42768: enforce implicit rejection for CMS and PKCS#7 RSA PKCS#1 v1.5 decryption

• CVE-2026-34180: fix heap buffer over-read in ASN.1 content parsing caused by truncating a long content length to int
• CVE-2026-7383: fix heap buffer overflow in ASN1_mbstring_ncopy() caused by signed integer overflow when computing the output length
• CVE-2026-42766: fix NULL pointer dereference when keyDerivationAlgorithm is absent in CMS PasswordRecipientInfo
• CVE-2026-9076: fix out-of-bounds read in kek_unwrap_key() check-byte validation for KEK ciphers with a block size below 4 octets
• CVE-2026-42768: enforce implicit rejection for CMS and PKCS#7 RSA PKCS#1 v1.5 decryption

The updated packages fix security vulnerabilities: Possible Heap Buffer Overflow in ASN.1 Multibyte String Conversion. (CVE-2026-7383) Out-of-Bounds Read in CMS Password-Based Decryption. (CVE-2026-9076) Heap Buffer Over-read in ASN.1 Content Parsing. (CVE-2026-34180) PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys. (CVE-2026-34181) CMS AuthEnvelopedData Processing May Accept Forged Messages. (CVE-2026-34182) Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler. (CVE-2026-34183) NULL Pointer Dereference in QUIC Server Initial Packet Handling. (CVE-2026-42764) Possible NULL Dereference in Password-Based CMS Decryption. (CVE-2026-42766) NULL Pointer Dereference in CRMF EncryptedValue Decryption. (CVE-2026-42767) Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt(). (CVE-2026-42768) Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate. (CVE-2026-42769) FFC-DH Peer Validation Uses Attacker-Supplied q. (CVE-2026-42770) AES-OCB IV Ignored on EVP_Cipher() Path. (CVE-2026-45445) Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes. (CVE-2026-45446) Heap Use-After-Free in the PKCS7_verify(). (CVE-2026-45447)

These are all security issues fixed in the libopenssl-3-devel-3.5.3-6.1 package on the GA media of openSUSE Tumbleweed.

This update for openssl-3 fixes the following issues

• CVE-2026-2673: TLS 1.3 servers may choose unexpected key agreement group (bsc#1259652).
• CVE-2026-7383: Possible Heap Buffer Overflow in ASN.1 Multibyte String Conversion (bsc#1266340).
• CVE-2026-9076: Out-of-Bounds Read in CMS Password-Based Decryption (bsc#1266341).
• CVE-2026-34180: Heap Buffer Over-read in ASN.1 Content Parsing (bsc#1266342).
• CVE-2026-34182: CMS AuthEnvelopedData Processing May Accept Forged Messages (bsc#1266344).
• CVE-2026-34183: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (bsc#1266345).
• CVE-2026-42764: NULL pointer dereference in QUIC server initial packet handling (bsc#1266347).
• CVE-2026-42766: Possible NULL Dereference in Password-Based CMS Decryption (bsc#1266349).
• CVE-2026-42767: NULL Pointer Dereference in CRMF EncryptedValue Decryption (bsc#1266350).
• CVE-2026-42768: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (bsc#1266351).
• CVE-2026-42769: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (bsc#1266352).
• CVE-2026-42770: FFC-DH Peer Validation Uses Attacker-Supplied q (bsc#1266353).
• CVE-2026-45445: AES-OCB IV Ignored on EVP_Cipher() Path (bsc#1266355).
• CVE-2026-45446: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (bsc#1266356).
• CVE-2026-45447: Heap Use-After-Free in OpenSSL PKCS7_verify() (bsc#1266357).

This update for openssl-3 fixes the following issues

• CVE-2026-2673: TLS 1.3 servers may choose unexpected key agreement group (bsc#1259652).
• CVE-2026-7383: Possible Heap Buffer Overflow in ASN.1 Multibyte String Conversion (bsc#1266340).
• CVE-2026-9076: Out-of-Bounds Read in CMS Password-Based Decryption (bsc#1266341).
• CVE-2026-34180: Heap Buffer Over-read in ASN.1 Content Parsing (bsc#1266342).
• CVE-2026-34182: CMS AuthEnvelopedData Processing May Accept Forged Messages (bsc#1266344).
• CVE-2026-34183: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (bsc#1266345).
• CVE-2026-42764: NULL pointer dereference in QUIC server initial packet handling (bsc#1266347).
• CVE-2026-42766: Possible NULL Dereference in Password-Based CMS Decryption (bsc#1266349).
• CVE-2026-42767: NULL Pointer Dereference in CRMF EncryptedValue Decryption (bsc#1266350).
• CVE-2026-42768: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (bsc#1266351).
• CVE-2026-42769: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (bsc#1266352).
• CVE-2026-42770: FFC-DH Peer Validation Uses Attacker-Supplied q (bsc#1266353).
• CVE-2026-45445: AES-OCB IV Ignored on EVP_Cipher() Path (bsc#1266355).
• CVE-2026-45446: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (bsc#1266356).
• CVE-2026-45447: Heap Use-After-Free in OpenSSL PKCS7_verify() (bsc#1266357).

This update for openssl-3 fixes the following issues

• CVE-2026-2673: TLS 1.3 servers may choose unexpected key agreement group (bsc#1259652).
• CVE-2026-7383: Possible Heap Buffer Overflow in ASN.1 Multibyte String Conversion (bsc#1266340).
• CVE-2026-9076: Out-of-Bounds Read in CMS Password-Based Decryption (bsc#1266341).
• CVE-2026-34180: Heap Buffer Over-read in ASN.1 Content Parsing (bsc#1266342).
• CVE-2026-34182: CMS AuthEnvelopedData Processing May Accept Forged Messages (bsc#1266344).
• CVE-2026-34183: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (bsc#1266345).
• CVE-2026-42764: NULL pointer dereference in QUIC server initial packet handling (bsc#1266347).
• CVE-2026-42766: Possible NULL Dereference in Password-Based CMS Decryption (bsc#1266349).
• CVE-2026-42767: NULL Pointer Dereference in CRMF EncryptedValue Decryption (bsc#1266350).
• CVE-2026-42768: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (bsc#1266351).
• CVE-2026-42769: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (bsc#1266352).
• CVE-2026-42770: FFC-DH Peer Validation Uses Attacker-Supplied q (bsc#1266353).
• CVE-2026-45445: AES-OCB IV Ignored on EVP_Cipher() Path (bsc#1266355).
• CVE-2026-45446: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (bsc#1266356).
• CVE-2026-45447: Heap Use-After-Free in OpenSSL PKCS7_verify() (bsc#1266357).

This update for openssl-3 fixes the following issues

• CVE-2026-7383: Possible Heap Buffer Overflow in ASN.1 Multibyte String Conversion (bsc#1266340).
• CVE-2026-9076: Out-of-Bounds Read in CMS Password-Based Decryption (bsc#1266341).
• CVE-2026-34180: Heap Buffer Over-read in ASN.1 Content Parsing (bsc#1266342).
• CVE-2026-34181: PKCS#12 Files with PBMAC1 Are Accepted with Short HMAC Keys (bsc#1266343).
• CVE-2026-34183: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler (bsc#1266345).
• CVE-2026-42766: Possible NULL Dereference in Password-Based CMS Decryption (bsc#1266349).
• CVE-2026-42767: NULL Pointer Dereference in CRMF EncryptedValue Decryption (bsc#1266350).
• CVE-2026-42768: Multi-RecipientInfo Bleichenbacher Oracle in CMS_decrypt() and PKCS7_decrypt() (bsc#1266351).
• CVE-2026-42769: Trust-Anchor Substitution via cert/issuer Typo in CMP rootCaKeyUpdate (bsc#1266352).
• CVE-2026-42770: FFC-DH Peer Validation Uses Attacker-Supplied q (bsc#1266353).
• CVE-2026-45445: AES-OCB IV Ignored on EVP_Cipher() Path (bsc#1266355).
• CVE-2026-45446: Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes (bsc#1266356).
• CVE-2026-45447: Heap Use-After-Free in OpenSSL PKCS7_verify() (bsc#1266357).