{"attribution":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","cve":{"id":"CVE-2026-56820","sourceIdentifier":"security-advisories@github.com","published":"2026-07-21T23:17:52.403","lastModified":"2026-07-30T14:48:49.323","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"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."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"netty","product":"netty","versions":[{"version":"\u003e= 4.2.0.Final, \u003c 4.2.16.Final","status":"affected"},{"version":"\u003c 4.1.136.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},{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","baseScore":9.1,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":3.9,"impactScore":5.2}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-07-24T03:55:59.408001Z","id":"CVE-2026-56820","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-295"}]}],"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/commit/5b68c61f37aa4a3045cba624cbea239655c9003b","source":"security-advisories@github.com","tags":["Patch"]},{"url":"https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6","source":"security-advisories@github.com","tags":["Patch"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.1.136.Final","source":"security-advisories@github.com","tags":["Release Notes"]},{"url":"https://github.com/netty/netty/releases/tag/netty-4.2.16.Final","source":"security-advisories@github.com","tags":["Release Notes"]},{"url":"https://github.com/netty/netty/security/advisories/GHSA-272m-gcwp-mpwg","source":"security-advisories@github.com","tags":["Exploit","Vendor Advisory"]}]}}