CVE-2026-63076: Invalid Pointer Dereference in CMP Server via Crafted protectionAlg
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.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this denial-of-service condition?
Applications acting as CMP servers are exposed if they accept PBM-protected CMP messages and PBM verification is reachable. CMP clients can also be affected when communicating with a malicious or intercepted CMP server.
Does an attacker need the PBM shared secret to trigger the issue?
No. The invalid parameter is processed during protection verification before any MAC is computed, so knowledge of the PBM shared secret is not required.
What kind of input triggers the crash?
The attacker must supply a CMP message whose protectionAlg parameter is present but has a type other than the expected PBMParameter. The affected verification path casts and dereferences that value without checking its ASN.1 type.