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CVE-2026-4395

Heap-based buffer overflow in wc_ecc_import_x963_ex KCAPI path

1.3 LowFix available

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
Low

Exploit likelihood

0.36%Up 0.2 points since Mar 20, 2026
90%50%10%1%

What each source reports

CVE List Score used 1.3

Heap-based buffer overflow in wc_ecc_import_x963_ex KCAPI path

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
CVE-2026-4395
CVSS 4.0
1.3 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/AU:Y/R:U/V:D/RE:L/U:Amber
Weakness
CWE-122
Updated
2026-11-02
EUVDEUVD-2026-13235 1.3

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
EUVD-2026-13235
CVSS 4.0
1.3 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/AU:Y/R:U/V:D/RE:L/U:Amber
Updated
2026-11-02
GitHub AdvisoriesGHSA-cqx9-3cpj-rrqp 1.3

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL...

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
GHSA-cqx9-3cpj-rrqp
CVSS 4.0
1.3 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:D/RE:L/U:Amber
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-122
Updated
2026-11-02
NVD 1.3

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
CVE-2026-4395
CVSS 4.0
1.3 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:D/RE:L/U:Amber
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-122
Updated
2026-11-02
OSVALPINE-CVE-2026-4395 9.8

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
ALPINE-CVE-2026-4395
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-03
OSV 1.3

Heap-based buffer overflow in wc_ecc_import_x963_ex KCAPI path

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
CVE-2026-4395
CVSS 4.0
1.3 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/AU:Y/R:U/V:D/RE:L/U:Amber
Weakness
CWE-122
Updated
2026-11-02
OSVDEBIAN-CVE-2026-4395 9.8

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
DEBIAN-CVE-2026-4395
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVJLSEC-2026-713 1.3

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
JLSEC-2026-713
CVSS 4.0
1.3 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:D/RE:L/U:Amber
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-4395 1.3

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

Record
UBUNTU-CVE-2026-4395
CVSS 4.0
1.3 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/AU:Y/R:U/V:D/RE:L/U:Amber
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
wolfssl
Alpine:v3.23
before 5.9.1-r0
5.9.1-r0
wolfssl
Alpine:v3.24
before 5.9.0-r0
5.9.0-r0
wolfssl
Debian:12
All versions, plus listed versions
5.5.4-25.5.4-2+deb12u15.5.4-2+deb12u25.5.4-2+deb12u35.5.4-2.1
Show 22 moreShow less
5.6.4-15.6.4-25.6.6-15.6.6-1.15.6.6-1.25.6.6-1.35.6.6-1.3~exp15.7.0-0.15.7.0-0.25.7.0-0.35.7.2-0.15.7.2-0.25.7.2-0.35.7.2-0.45.8.2-15.8.2-1.15.8.2-1.25.8.4-15.9.0-0.15.9.0-0.25.9.1-0.15.9.2-1
None known
wolfssl
Debian:13
All versions, plus listed versions
5.7.2-0.15.7.2-0.1+deb13u15.7.2-0.1+deb13u25.7.2-0.25.7.2-0.3
Show 9 moreShow less
5.7.2-0.45.8.2-15.8.2-1.15.8.2-1.25.8.4-15.9.0-0.15.9.0-0.25.9.1-0.15.9.2-1
None known
wolfSSL_jll
Julia
before 5.9.2+0
5.9.2+0
wolfssl
Ubuntu:16.04:LTS
All versions, plus listed versions
3.4.8+dfsg-1
None known
wolfssl
Ubuntu:18.04:LTS
All versions, plus listed versions
3.10.2+dfsg-23.12.0+dfsg-13.12.2+dfsg-13.13.0+dfsg-1
None known
wolfssl
Ubuntu:20.04:LTS
All versions, plus listed versions
4.1.0+dfsg-24.2.0+dfsg-14.2.0+dfsg-24.2.0+dfsg-34.3.0+dfsg-2
None known
wolfssl
Ubuntu:22.04:LTS
All versions, plus listed versions
4.6.0-35.0.0-15.1.1-15.2.0-15.2.0-2
None known
wolfssl
Ubuntu:24.04:LTS
All versions, plus listed versions
5.5.4-25.5.4-2.15.6.4-25.6.6-1.25.6.6-1.35.6.6-1.3build1
None known
wolfssl
Ubuntu:25.10
All versions, plus listed versions
5.7.2-0.1
None known
wolfssl
Ubuntu:26.10
All versions, plus listed versions
5.9.1-0.15.9.2-1
None known
wolfssl
Ubuntu:26.04:LTS
All versions, plus listed versions
5.7.2-0.15.8.2-1.25.8.4-15.9.1-0.1
None known

History

History
RecordedChangedSources
affected, aliases, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-4395 is a low vulnerability (CVSS 1.3) in Wolfssl, published March 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.36%, the 29th percentile. Fixed in wolfssl 5.9.1-r0.

References

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