CVE-2026-28389

Issue summary: During processing of a crafted CMS EnvelopedData message<br /> with KeyAgreeRecipientInfo a NULL pointer dereference can happen.<br /> <br /> Impact summary: Applications that process attacker-controlled CMS data may<br /> crash before authentication or cryptographic operations occur resulting in<br /> Denial of Service.<br /> <br /> When a CMS EnvelopedData message that uses KeyAgreeRecipientInfo is<br /> processed, the optional parameters field of KeyEncryptionAlgorithmIdentifier<br /> is examined without checking for its presence. This results in a NULL<br /> pointer dereference if the field is missing.<br /> <br /> Applications and services that call CMS_decrypt() on untrusted input<br /> (e.g., S/MIME processing or CMS-based protocols) are vulnerable.<br /> <br /> The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this<br /> issue, as the affected code is outside the OpenSSL FIPS module boundary.