{"cve":"CVE-2026-56820","nvd":{"published":"2026-07-21T23:17:52.403","modified":"2026-07-30T14:48:49.323","status":"Analyzed","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","score":9.1},"cwes":["CWE-295"],"references":["https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b","https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6","https://github.com/netty/netty/releases/tag/netty-4.1.136.Final","https://github.com/netty/netty/releases/tag/netty-4.2.16.Final","https://github.com/netty/netty/security/advisories/GHSA-272m-gcwp-mpwg"],"products":["netty:netty"],"source":"nvd","synced_at":"2026-10-19T22:45:53.305392138+00:00"},"epss":{"cve":"CVE-2026-56820","score":0.00313,"percentile":0.2422,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-272m-gcwp-mpwg","url":"https://osv.dev/vulnerability/GHSA-272m-gcwp-mpwg","summary":"Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks","modified":"2026-09-10T03:51:10.059541420Z","packages":[{"ecosystem":"Maven","name":"io.netty:netty-handler-ssl-ocsp","purl":"pkg:maven/io.netty/netty-handler-ssl-ocsp","ranges":[">=4.2.0.Final <4.2.16.Final"],"fixed":["4.2.16.Final"]},{"ecosystem":"Maven","name":"io.netty:netty-handler-ssl-ocsp","purl":"pkg:maven/io.netty/netty-handler-ssl-ocsp","ranges":["<4.1.136.Final"],"fixed":["4.1.136.Final"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}