{"api_version":"1","generated_at":"2026-08-02T04:41:09+00:00","cve":"CVE-2026-56821","urls":{"html":"https://cve.report/CVE-2026-56821","api":"https://cve.report/api/cve/CVE-2026-56821.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-56821","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-56821"},"summary":{"title":"Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator","description":"Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, the OcspServerCertificateValidator flags an out-of-date OCSP response but does not stop processing it, so an expired GOOD response is still reported as VALID, letting an on-path attacker replay a stale GOOD response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.","state":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-07-29 00:16:38","updated_at":"2026-07-31 16:17:07"},"problem_types":["CWE-299","CWE-299 CWE-299: Improper Check for Certificate Revocation"],"metrics":[{"version":"3.1","source":"security-advisories@github.com","type":"Secondary","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","data":{"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"}},{"version":"3.1","source":"CNA","type":"DECLARED","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","data":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"references":[{"url":"https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr","name":"https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr","refsource":"134c704f-9b21-4f2e-91b3-4a467353bcc0","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-56821","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56821","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"netty","product":"netty","version":"affected < 4.1.136.Final","platforms":[]},{"source":"CNA","vendor":"netty","product":"netty","version":"affected >= 4.2.0.Final, < 4.2.16.Final","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"56821","cve":"CVE-2026-56821","epss":"0.001400000","percentile":"0.038310000","score_date":"2026-08-01","updated_at":"2026-08-02 00:11:12"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-56821","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","timestamp":"2026-07-30T03:55:19.093244Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-07-31T16:12:56.878Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"references":[{"tags":["exploit"],"url":"https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr"}],"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"product":"netty","vendor":"netty","versions":[{"status":"affected","version":"< 4.1.136.Final"},{"status":"affected","version":">= 4.2.0.Final, < 4.2.16.Final"}]}],"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."}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-299","description":"CWE-299: Improper Check for Certificate Revocation","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-07-29T17:32:19.753Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M"},"references":[{"name":"https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr","tags":["x_refsource_CONFIRM"],"url":"https://github.com/netty/netty/security/advisories/GHSA-g7hg-vrcf-mvmr"}],"source":{"advisory":"GHSA-g7hg-vrcf-mvmr","discovery":"UNKNOWN"},"title":"Netty: Out-of-date OCSP Responses Accepted by OcspServerCertificateValidator"}},"cveMetadata":{"assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","assignerShortName":"GitHub_M","cveId":"CVE-2026-56821","datePublished":"2026-07-28T23:07:13.616Z","dateReserved":"2026-06-23T14:55:09.116Z","dateUpdated":"2026-07-31T16:12:56.878Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-29 00:16:38","lastModifiedDate":"2026-07-31 16:17:07","problem_types":["CWE-299","CWE-299 CWE-299: Improper Check for Certificate Revocation"],"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"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"56821","Ordinal":"1","Title":"Netty: Out-of-date OCSP Responses Accepted by OcspServerCertific","CVE":"CVE-2026-56821","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"56821","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"Netty: Out-of-date OCSP Responses Accepted by OcspServerCertific"}]}}}