CVE-2026-28389

Name of the Vulnerable Software and Affected Versions OpenSSL versions 3.0 through 3.6

Description Processing a crafted CMS EnvelopedData message with KeyAgreeRecipientInfo can lead to a NULL pointer dereference. This can cause applications that process attacker-controlled CMS data to crash before authentication or cryptographic operations, resulting in a Denial of Service. The issue occurs when the optional parameters field of KeyEncryptionAlgorithmIdentifier is examined without checking for its presence, leading to a NULL pointer dereference if the field is missing. Applications and services calling CMS decrypt() on untrusted input, such as S/MIME processing or CMS-based protocols, are affected.

Recommendations Update to a version after 3.6. As a temporary workaround, avoid processing untrusted CMS EnvelopedData messages with KeyAgreeRecipientInfo.