{"id":"CVE-2026-114618","state":"PUBLISHED","title":"Authlib: Default JWT bearer grant accepts assertions for the wrong audience","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, the default RFC 7523 JWTBearerGrant.get_audiences() returns an empty list, causing JWTBearerGrant.verify_claims() to require only that an aud claim exists without matching the current authorization server. An attacker holding a legitimate assertion for another service can present it to a server that shares the signing key and uses the default grant, obtaining an access token across a trust boundary. Implementations that override get_audiences() with the server's valid audience identifiers are not affected. This issue is fixed in version 1.9.0.","publishedAt":"2026-10-22T21:28:37.879Z","updatedAt":"2026-10-29T12:29:17.976Z","severity":{"score":6.8,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["authlib authlib"],"affected":[{"vendor":"authlib","product":"authlib","versions":[{"version":"< 1.9.0","status":"affected"}]}],"references":["https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc","https://github.com/authlib/authlib/pull/945","https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf","https://github.com/authlib/authlib/releases/tag/v1.9.0"],"weaknesses":["CWE-287","CWE-1188"],"ingestedAt":"2026-10-29T20:10:43.281Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/114xxx/CVE-2026-114618.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-114618","state":"PUBLISHED","datePublished":"2026-10-22T21:28:37.879Z","dateUpdated":"2026-10-29T12:29:17.976Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-21T20:34:25.600Z"},"containers":{"cna":{"title":"Authlib: Default JWT bearer grant accepts assertions for the wrong audience","descriptions":[{"lang":"en","value":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, the default RFC 7523 JWTBearerGrant.get_audiences() returns an empty list, causing JWTBearerGrant.verify_claims() to require only that an aud claim exists without matching the current authorization server. An attacker holding a legitimate assertion for another service can present it to a server that shares the signing key and uses the default grant, obtaining an access token across a trust boundary. Implementations that override get_audiences() with the server's valid audience identifiers are not affected. This issue is fixed in version 1.9.0."}],"affected":[{"vendor":"authlib","product":"authlib","versions":[{"version":"< 1.9.0","status":"affected"}]}],"references":[{"url":"https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc","name":"https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/authlib/authlib/pull/945","name":"https://github.com/authlib/authlib/pull/945","tags":["x_refsource_MISC"]},{"url":"https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf","name":"https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf","tags":["x_refsource_MISC"]},{"url":"https://github.com/authlib/authlib/releases/tag/v1.9.0","name":"https://github.com/authlib/authlib/releases/tag/v1.9.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.8,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-287","lang":"en","description":"CWE-287: Improper Authentication","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-1188","lang":"en","description":"CWE-1188: Insecure Default Initialization of Resource","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-22T21:28:37.879Z"},"source":{"advisory":"GHSA-fch4-3c6x-j4gc","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-29T12:28:44.727870Z","id":"CVE-2026-114618","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-29T12:29:17.976Z"}}]}}}