{"id":"CVE-2026-56820","aliases":["GHSA-272m-gcwp-mpwg"],"url":"https://o3.security/vulnerability/CVE-2026-56820","summary":"Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks","details":"Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and prior to 4.1.135.Final, `OcspClient` does not validate that the `CertificateID` in an OCSP response matches the requested `CertificateID`, which can lead to replay attack. `OcspClient.validateResponse` accepts a legitimately signed `GOOD` status response for an unrelated certificate issued by the same CA, allowing bypass of revocation checks for another certificate. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.","published":"2026-07-21T22:26:16.588Z","modified":"2026-08-12T16:41:29.817406Z","cvss":{"score":7.4,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},"epss":{"score":0.0022,"percentile":0.12448,"asOf":"2026-09-04"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"io.netty:netty-handler-ssl-ocsp","fixedVersion":"4.2.16.Final"},{"ecosystem":"Maven","name":"io.netty:netty-handler-ssl-ocsp","fixedVersion":"4.1.136.Final"}],"fix":{"url":"https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b","label":"netty/netty@5b68c61"},"references":[{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.1.136.Final"},{"type":"WEB","url":"https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56820.json"},{"type":"ADVISORY","url":"https://github.com/netty/netty/security/advisories/GHSA-272m-gcwp-mpwg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56820"},{"type":"FIX","url":"https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b"},{"type":"FIX","url":"https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T16:41:29.817406Z"}}