CVE-2026-63076

Technical Description

Issue summary: OpenSSL CMP password based protection verification only

checks whether the protectionAlg parameter was not NULL and not its

ASN.1 type, before treating it as a PBMParameter. A crafted message can

contain a parameter of a different type, which is then dereferenced as an

invalid pointer.

Impact summary: A remote, unauthenticated attacker can crash an application

acting as a CMP server that accepts PBM-protected messages, or a CMP client

talking to a malicious or intercepted CMP server, resulting in a Denial of

Service.

CWE: CWE-476: NULL Pointer Dereference

Description: When verifying the password-based MAC protection of a CMP

message, OpenSSL library reads the protectionAlg algorithm parameter with

X509_ALGOR_get0(), which returns both the parameter type and its value

pointer. The value is then cast to an ASN1_STRING and treated as the

expected PBMParameter after only checking that pointer is not NULL. The

parameter type returned by X509_ALGOR_get0() was never consulte

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References