{"id":"CVE-2026-75509","state":"PUBLISHED","title":"joserfc claim-validation bypass via array-typed single-string claims (iss/sub/jti)","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3.","publishedAt":"2026-08-24T20:08:07.088Z","updatedAt":"2026-08-25T16:42:19.769Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["authlib joserfc"],"affected":[{"vendor":"authlib","product":"joserfc","versions":[{"version":"< 1.7.3","status":"affected"}]}],"references":["https://github.com/authlib/joserfc/security/advisories/GHSA-r74j-q665-7rpj","https://github.com/authlib/joserfc/commit/76ee6a59bf5773c0af00b99076c5e199031f97f1"],"weaknesses":["CWE-290","CWE-345"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/75xxx/CVE-2026-75509.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-75509","state":"PUBLISHED","datePublished":"2026-08-24T20:08:07.088Z","dateUpdated":"2026-08-25T16:42:19.769Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-17T20:49:21.598Z"},"containers":{"cna":{"title":"joserfc claim-validation bypass via array-typed single-string claims (iss/sub/jti)","descriptions":[{"lang":"en","value":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3."}],"affected":[{"vendor":"authlib","product":"joserfc","versions":[{"version":"< 1.7.3","status":"affected"}]}],"references":[{"url":"https://github.com/authlib/joserfc/security/advisories/GHSA-r74j-q665-7rpj","name":"https://github.com/authlib/joserfc/security/advisories/GHSA-r74j-q665-7rpj","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/authlib/joserfc/commit/76ee6a59bf5773c0af00b99076c5e199031f97f1","name":"https://github.com/authlib/joserfc/commit/76ee6a59bf5773c0af00b99076c5e199031f97f1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-290","lang":"en","description":"CWE-290: Authentication Bypass by Spoofing","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-345","lang":"en","description":"CWE-345: Insufficient Verification of Data Authenticity","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-24T20:08:07.088Z"},"source":{"advisory":"GHSA-r74j-q665-7rpj","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/authlib/joserfc/security/advisories/GHSA-r74j-q665-7rpj","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-25T16:38:57.782770Z","id":"CVE-2026-75509","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-25T16:42:19.769Z"}}]}}}