CVE-2025-5987

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

The ssh library was designed to be used by programmers needing a working SSH implementation by the mean of a library. The complete control of the client is made by the programmer. With libssh, you can remotely execute programs, transfer files, use a secure and transparent tunnel for your remote programs. With its Secure FTP implementation, you can play with remote files easily, without third-party programs others than libcrypto (from openssl).

Security Fix(es):

A vulnerability classified as critical was found in libssh up to 0.11.1.The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer.As an impact it is known to affect confidentiality, integrity, and availability.Upgrading to version 0.11.2 eliminates this vulnerability.(CVE-2025-4877)

A vulnerability, which was classified as problematic, has been found in libssh up to 0.11.1.Using CWE to declare the problem leads to CWE-824. The product accesses or uses a pointer that has not been initialized.Impacted is confidentiality, integrity, and availability.Upgrading to version 0.11.2 eliminates this vulnerability.(CVE-2025-4878)

A flaw was found in the key export functionality of libssh. The issue occurs in the internal function responsible for converting cryptographic keys into serialized formats. During error handling, a memory structure is freed but not cleared, leading to a potential double free issue if an additional failure occurs later in the function. This condition may result in heap corruption or application instability in low-memory scenarios, posing a risk to system reliability where key export operations are performed.(CVE-2025-5351)

A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails. This results in uninitialized cryptographic key buffers being used in subsequent communication, potentially compromising SSH sessions' confidentiality, integrity, and availability.(CVE-2025-5372)

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.(CVE-2025-5987)

The ssh library was designed to be used by programmers needing a working SSH implementation by the mean of a library. The complete control of the client is made by the programmer. With libssh, you can remotely execute programs, transfer files, use a secure and transparent tunnel for your remote programs. With its Secure FTP implementation, you can play with remote files easily, without third-party programs others than libcrypto (from openssl).

Security Fix(es):

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.(CVE-2025-5987)

The ssh library was designed to be used by programmers needing a working SSH implementation by the mean of a library. The complete control of the client is made by the programmer. With libssh, you can remotely execute programs, transfer files, use a secure and transparent tunnel for your remote programs. With its Secure FTP implementation, you can play with remote files easily, without third-party programs others than libcrypto (from openssl).

Security Fix(es):

A vulnerability classified as critical was found in libssh up to 0.11.1.The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer.As an impact it is known to affect confidentiality, integrity, and availability.Upgrading to version 0.11.2 eliminates this vulnerability.(CVE-2025-4877)

A vulnerability, which was classified as problematic, has been found in libssh up to 0.11.1.Using CWE to declare the problem leads to CWE-824. The product accesses or uses a pointer that has not been initialized.Impacted is confidentiality, integrity, and availability.Upgrading to version 0.11.2 eliminates this vulnerability.(CVE-2025-4878)

A flaw was found in the key export functionality of libssh. The issue occurs in the internal function responsible for converting cryptographic keys into serialized formats. During error handling, a memory structure is freed but not cleared, leading to a potential double free issue if an additional failure occurs later in the function. This condition may result in heap corruption or application instability in low-memory scenarios, posing a risk to system reliability where key export operations are performed.(CVE-2025-5351)

A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails. This results in uninitialized cryptographic key buffers being used in subsequent communication, potentially compromising SSH sessions' confidentiality, integrity, and availability.(CVE-2025-5372)

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.(CVE-2025-5987)

libssh is a library which implements the SSH protocol. It can be used to implement client and server applications.

Security Fix(es):

• libssh: Invalid return code for chacha20 poly1305 with OpenSSL backend (CVE-2025-5987)

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.

libssh is a library which implements the SSH protocol. It can be used to implement client and server applications.

Security Fix(es):

• libssh: Invalid return code for chacha20 poly1305 with OpenSSL backend (CVE-2025-5987)

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.

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

libssh is a library which implements the SSH protocol. It can be used to implement client and server applications.

Security Fix(es):

• libssh: Invalid return code for chacha20 poly1305 with OpenSSL backend (CVE-2025-5987)

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.

libssh is a library which implements the SSH protocol. It can be used to implement client and server applications.

Security Fix(es):

• libssh: Invalid return code for chacha20 poly1305 with OpenSSL backend (CVE-2025-5987)

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.

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

• CVE-2025-5987: fix missing error detection in ChaCha20 initialization that could leave cipher context partially uninitialized

• CVE-2025-5372: fix inconsistent return value interpretation in ssh_kdf() function to prevent uninitialized key buffers leading to SSH session compromise
• CVE-2025-5987: fix missing error detection in ChaCha20 initialization that could leave cipher context partially uninitialized

CVE-2025-4877 Write beyond bounds in binary to base64 conversion functions CVE-2025-4878 Use of uninitialized variable in privatekey_from_file() CVE-2025-5318 Likely read beyond bounds in sftp server handle management CVE-2025-5351 Double free in functions exporting keys CVE-2025-5372 ssh_kdf() returns a success code on certain failures CVE-2025-5449 Likely read beyond bounds in sftp server message decoding CVE-2025-5987 Invalid return code for chacha20 poly1305 with OpenSSL backend

These are all security issues fixed in the libssh-config-0.11.2-1.1 package on the GA media of openSUSE Tumbleweed.

Root has patched CVE-2025-5987 in the libssh package for Root:Debian:11. Multiple fixed versions available.

Root has patched CVE-2025-5987 in the libssh package for Root:Debian:12. Multiple fixed versions available.

This update for libssh fixes the following issues:

• CVE-2025-5372: ssh_kdf() returns a success code on certain failures (bsc#1245314)
• CVE-2025-5987: Invalid return code for chacha20 poly1305 with OpenSSL backend (bsc#1245317)
• CVE-2025-4877: Write beyond bounds in binary to base64 conversion functions (bsc#1245309)
• CVE-2025-4878: Use of uninitialized variable in privatekey_from_file() (bsc#1245310)
• CVE-2025-5318: Likely read beyond bounds in sftp server handle management (bsc#1245311)
• CVE-2025-5351: Double free in functions exporting keys (bsc#1245312)

This update for libssh fixes the following issues:

• CVE-2025-5372: ssh_kdf() returns a success code on certain failures (bsc#1245314)
• CVE-2025-5987: Invalid return code for chacha20 poly1305 with OpenSSL backend (bsc#1245317)
• CVE-2025-4877: Write beyond bounds in binary to base64 conversion functions (bsc#1245309)
• CVE-2025-4878: Use of uninitialized variable in privatekey_from_file() (bsc#1245310)
• CVE-2025-5318: Likely read beyond bounds in sftp server handle management (bsc#1245311)
• CVE-2025-5351: Double free in functions exporting keys (bsc#1245312)

Ronald Crane discovered that libssh incorrectly handled certain base64 conversions. An attacker could use this issue to cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2025-4877)

Ronald Crane discovered that libssh incorrectly handled the privatekey_from_file() function. An attacker could use this issue to cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2025-4878)

Ronald Crane discovered that libssh incorrectly handled certain memory operations in the sftp server. An attacker could possibly use this issue to cause libssh to crash, resulting in a denial of service. (CVE-2025-5318, CVE-2025-5449)

Ronald Crane discovered that libssh incorrectly handled exporting keys. An attacker could possibly use this issue to cause libssh to crash, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 24.10, and Ubuntu 25.04. (CVE-2025-5351)

Ronald Crane discovered that libssh incorrectly handled the ssh_kdf() function. An attacker could use this issue to cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2025-5372)

Ronald Crane discovered that libssh incorrectly handled the ChaCha20 cipher. An attacker could possibly use this issue to cause libssh to use partially initialized cypher content. This issue only affected Ubuntu 24.04 LTS, Ubuntu 24.10, and Ubuntu 25.04. (CVE-2025-5987)