Vulnerability Description
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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Authlib | Authlib | < 1.9.0 |
Related Weaknesses (CWE)
References
- https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeePatch
- https://github.com/authlib/authlib/pull/945Patch
- https://github.com/authlib/authlib/releases/tag/v1.9.0Release Notes
- https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gcExploitVendor Advisory
- https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gcExploitVendor Advisory
FAQ
What is CVE-2026-114618?
CVE-2026-114618 is a vulnerability with a CVSS score of 6.8 (MEDIUM). 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_clai...
How severe is CVE-2026-114618?
CVE-2026-114618 has been rated MEDIUM with a CVSS base score of 6.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-114618?
Check the references section above for vendor advisories and patch information. Affected products include: Authlib Authlib.