medium6.8
CVE-2026-114618
Authlib: Default JWT bearer grant accepts assertions for the wrong audience
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | authlib | < 1.9.0 | 1.9.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Authlib | Authlib | before 1.9.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-fch4-3c6x-j4gc
- https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc
- https://nvd.nist.gov/vuln/detail/CVE-2026-114618
- https://github.com/authlib/authlib/pull/945
- https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf
- https://github.com/authlib/authlib/releases/tag/v1.9.0