Threats tagged 'ghsa-fch4-3c6x-j4gc'

Authlib versions prior to 1.9.0 have a vulnerability in the default JWT bearer grant implementation where the audience ('aud') claim in JWT assertions is not properly validated. The default get_audiences() method returns an empty list, causing verify_claims() to only check for the presence of an 'aud' claim rather than verifying it matches the authorization server's token endpoint. This allows an attacker with a valid JWT for any audience to obtain an access token from a different authorization server sharing the same signing key.