MEDIUM 6.8 NVD
CVE-2026-114618
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
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.
References
- https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf
- https://github.com/authlib/authlib/pull/945
- https://github.com/authlib/authlib/releases/tag/v1.9.0
- https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc
This medium severity vulnerability with a CVSS score of 6.8 was published on 2026-10-22 via NVD.
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