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 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.