CVE-2026-114618
Authlib: Default JWT bearer grant accepts assertions for the wrong audience
- State
- Published
- Severity
- 6.8 Medium
- Published
- Oct 22, 2026
- Updated
- Oct 29, 2026
- Reserved
- Oct 21, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.8 Medium | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
authlibauthlib |
|
References
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