{"attribution":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","cve":{"id":"CVE-2026-56821","sourceIdentifier":"security-advisories@github.com","published":"2026-07-29T00:16:38.573","lastModified":"2026-08-07T15:05:53.920","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response to bypass revocation of a since-revoked certificate. Exploitation can lead to certificate revocation bypass via replay of an expired OCSP response. Any application using OcspServerCertificateValidator is affected; a revoked certificate can be accepted. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"netty","product":"netty","versions":[{"version":"\u003c 4.1.136.Final","status":"affected"},{"version":"\u003e= 4.2.0.Final, \u003c 4.2.16.Final","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","baseScore":7.4,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":2.2,"impactScore":5.2}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-07-30T03:55:19.093244Z","id":"CVE-2026-56821","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-299"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*","versionEndExcluding":"4.1.136","matchCriteriaId":"3A15093F-C6A7-4FCF-81BA-939CD522D1DD"},{"vulnerable":true,"criteria":"cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2.0","versionEndExcluding":"4.2.16","matchCriteriaId":"4DE4BC35-4405-49B5-A2A8-A700C7F63C8B"}]}]}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr","source":"security-advisories@github.com","tags":["Exploit","Vendor Advisory"]},{"url":"https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","tags":["Exploit","Vendor Advisory"]}]}}