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 servers valid audience identifiers are not affected. This issue is fixed in version 1.9.0.
Weakness
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Authlib | Authlib | * | 1.9.0 (excluding) |
Potential Mitigations
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/114.html
- https://cwe.mitre.org/data/definitions/115.html
- https://cwe.mitre.org/data/definitions/151.html
- https://cwe.mitre.org/data/definitions/194.html
- https://cwe.mitre.org/data/definitions/22.html
- https://cwe.mitre.org/data/definitions/57.html
- https://cwe.mitre.org/data/definitions/593.html
- https://cwe.mitre.org/data/definitions/633.html
- https://cwe.mitre.org/data/definitions/650.html
- https://cwe.mitre.org/data/definitions/94.html
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
- https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc