{"id":"CVE-2026-114618","title":"Authlib: Default JWT bearer grant accepts assertions for the wrong audience","summary":"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 clai…","severity":"medium","cvss":6.8,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","cvssSource":"cna","cwe":["CWE-287","CWE-1188"],"vendor":"authlib","product":"authlib","affected":["authlib < 1.9.0"],"published":"2026-10-22","updated":"2026-10-22","sourceUpdated":"2026-10-22T21:28:37.879Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-114618","references":[{"url":"https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc","label":"https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc"},{"url":"https://github.com/authlib/authlib/pull/945","label":"https://github.com/authlib/authlib/pull/945"},{"url":"https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf","label":"https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf"},{"url":"https://github.com/authlib/authlib/releases/tag/v1.9.0","label":"https://github.com/authlib/authlib/releases/tag/v1.9.0"}],"tags":["cve.org"],"ingestedAt":"2026-10-22T22:00:50.448Z","slug":"CVE-2026-114618","body":"## Overview\n\nAuthlib 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.\n\n## Affected\n\n- `authlib < 1.9.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":37,"depthScoreParts":{"impact":37.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}