OpenSSL 3.6.2 Released to Patch Eight Security Vulnerabilities

OpenSSL has released version 3.6.2 on April 7, 2026, as a security patch update. This release is designed to resolve eight distinct vulnerabilities, with the project rating the most severe of these issues as Moderate. The update arrives approximately two and a half months after the release of OpenSSL 3.6.1, providing a critical update for organizations and developers who rely on the library for cryptographic operations and secure communications.

Breakdown of Fixed Vulnerabilities

The 3.6.2 release incorporates several bug fixes and mitigations addressing a variety of flaws, including memory management errors, buffer overflows, and incorrect failure handling. The following CVEs are addressed in this update:

• CVE-2026-31790: Fixed incorrect failure handling in RSA KEM RSASVE encapsulation. RSA KEM (Key Encapsulation Mechanism) is used to securely transmit symmetric keys via asymmetric cryptography.
• CVE-2026-2673: Fixed a loss of key agreement group tuple structure that occurred when the DEFAULT keyword was used in the server-side configuration of the key-agreement group list.
• CVE-2026-28386: Resolved an out-of-bounds read in AES-CFB-128 on x86-64 CPUs with AVX-512 support.
• CVE-2026-28387: Fixed a potential employ-after-free vulnerability in DANE client code.
• CVE-2026-28388: Fixed a NULL pointer dereference when processing a delta CRL (Certificate Revocation List).
• CVE-2026-28389: Fixed a possible NULL dereference when processing CMS KeyAgreeRecipientInfo.
• CVE-2026-28390: Fixed a possible NULL dereference when processing CMS KeyTransportRecipientInfo.
• CVE-2026-31789: Fixed a heap buffer overflow in hexadecimal conversion.

Deep Dive: The AES-CFB-128 Out-of-Bounds Read

One notable fix in this release concerns CVE-2026-28386. This vulnerability specifically affects x86-64 systems with AVX-512 and VAES instruction support. Applications using AES-CFB128 encryption or decryption could trigger an out-of-bounds read of up to 15 bytes when processing partial cipher blocks.

The impact of this specific flaw is rated as Low because it may trigger a crash leading to a Denial of Service (DoS) only if the input buffer ends at a memory page boundary and the subsequent page is unmapped. There is no information disclosure since the over-read bytes aren’t written to the output. CFB mode isn’t used in TLS/DTLS protocols, which instead use CBC, GCM, CCM, or ChaCha20-Poly1305.

Key Takeaways for Administrators

• Update Immediately: Organizations using OpenSSL 3.6.0 or 3.6.1 should move to version 3.6.2 to mitigate these vulnerabilities.
• Severity Level: While eight CVEs were patched, the highest severity is Moderate.
• Hardware Specifics: Users of x86-64 systems with AVX-512 support should be particularly aware of the AES-CFB-128 fix.
• FIPS Impact: The OpenSSL FIPS module in the 3.6 version is affected by CVE-2026-28386.

Frequently Asked Questions

Which versions are affected by these vulnerabilities?

The vulnerabilities, such as CVE-2026-28386, affect versions from 3.6.0 before the release of 3.6.2.

What is the most severe vulnerability in this release?

The OpenSSL project has rated the most severe issue in the 3.6.2 release as Moderate.

Does this update affect TLS/DTLS protocols?

Regarding the AES-CFB-128 out-of-bounds read (CVE-2026-28386), the issue does not affect TLS/DTLS protocols because they do not use CFB mode.