CVE-2026-63076
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.33%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 consulted. This happens during protection verification, before any MAC is computed, so no knowledge of the PBM shared secret is required; the only precondition is that PBM verification is reachable. On the server side this is reached from OSSL_CMP_SRV_process_request() for any application that stands up a CMP server accepting PBM-protected messages, and on the client side from CMP response validation against a malicious or on-path (MITM) server. The reliable consequence is a denial of service; there is no memory disclosure, no controlled memory write, and no path to code execution. CMP is a specialized feature that an application must explicitly enable. FIPS impact: no As the CMP code lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 1.33% probability · 69th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-476
- Affected
- openssl/openssl
- Source
- openssl-security@openssl.org
References
- https://github.com/openssl/openssl/commit/37882aa2e0256e1072442a8f62f7db45b995c45bPatch
- https://github.com/openssl/openssl/commit/a17cc8d612ecff6d94a9b7ca8b5283ddf5ff570ePatch
- https://github.com/openssl/openssl/commit/a1f348ccb328c3afbd4ba6883f9b7c813c043259Patch
- https://github.com/openssl/openssl/commit/a7af46a92d0ce19a90e669ef56d2576a07924226Patch
- https://github.com/openssl/openssl/commit/cdacfff557389abfa9e4615abded2ec984517d6cPatch
- https://openssl-library.org/news/secadv/20260825.txtVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.