CVE-2026-114618
mediumAuthlib is a Python library which builds OAuth and OpenID Connect servers.
Vendor / product: Authlib — authlib
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:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N Affected products
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
References
- https://github.com/authlib/authlib/commit/e3bd41cb29dcfee434453b135ffb487884baeedf security-advisories@github.com
- https://github.com/authlib/authlib/pull/945 security-advisories@github.com
- https://github.com/authlib/authlib/releases/tag/v1.9.0 security-advisories@github.com
- https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc security-advisories@github.com
- https://github.com/authlib/authlib/security/advisories/GHSA-fch4-3c6x-j4gc 134c704f-9b21-4f2e-91b3-4a467353bcc0