{"id":"CVE-2026-63076","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-63076","generatedAt":"2026-10-28T04:35:34.510Z","title":"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.","description":"Issue summary: OpenSSL CMP password based protection verification only\nchecks whether the protectionAlg parameter was not NULL and not its\nASN.1 type, before treating it as a PBMParameter. A crafted message can\ncontain a parameter of a different type, which is then dereferenced as an\ninvalid pointer.\n\nImpact summary: A remote, unauthenticated attacker can crash an application\nacting as a CMP server that accepts PBM-protected messages, or a CMP client\ntalking to a malicious or intercepted CMP server, resulting in a Denial of\nService.\n\nCWE: CWE-476: NULL Pointer Dereference\n\nDescription: When verifying the password-based MAC protection of a CMP\nmessage, OpenSSL library reads the protectionAlg algorithm parameter with\nX509_ALGOR_get0(), which returns both the parameter type and its value\npointer. The value is then cast to an ASN1_STRING and treated as the\nexpected PBMParameter after only checking that pointer is not NULL. The\nparameter type returned by X509_ALGOR_get0() was never consulted.\n\nThis happens during protection verification, before any MAC is computed, so\nno knowledge of the PBM shared secret is required; the only precondition is\nthat PBM verification is reachable. On the server side this is reached from\nOSSL_CMP_SRV_process_request() for any application that stands up a CMP\nserver accepting PBM-protected messages, and on the client side from CMP\nresponse validation against a malicious or on-path (MITM) server. The\nreliable consequence is a denial of service; there is no memory disclosure,\nno controlled memory write, and no path to code execution. CMP is a\nspecialized feature that an application must explicitly enable.\n\nFIPS impact: no\nAs the CMP code lives outside the FIPS module boundary, no FIPS modules\nare affected by this CVE.","published":"2026-08-25T13:19:27.000Z","lastModified":"2026-09-11T21:17:12.000Z","status":"Analyzed","sourceIdentifier":"openssl-security@openssl.org","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-476"],"affected":["openssl/openssl"],"epss":{"score":0.01602,"percentile":0.75685,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (1.60%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/openssl/openssl/commit/37882aa2e0256e1072442a8f62f7db45b995c45b","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/a17cc8d612ecff6d94a9b7ca8b5283ddf5ff570e","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/a1f348ccb328c3afbd4ba6883f9b7c813c043259","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/a7af46a92d0ce19a90e669ef56d2576a07924226","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://github.com/openssl/openssl/commit/cdacfff557389abfa9e4615abded2ec984517d6c","tags":["Patch"],"source":"openssl-security@openssl.org"},{"url":"https://openssl-library.org/news/secadv/20260825.txt","tags":["Vendor Advisory"],"source":"openssl-security@openssl.org"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63076","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}