Vulnerability Description
Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, OpenIDMixin.parse_id_token() reads the nonce_supported decision from the untrusted ID token being validated and sets the expected nonce to null when that claim is the JSON boolean false. In implicit and hybrid relying parties, or applications that directly accept externally supplied ID tokens, an attacker with a captured validly signed token can bypass the nonce-to-session binding and replay the victim's token into an attacker-controlled session. Plain authorization code flow is not affected, and the token must still pass signature, issuer, and audience validation. OpenIDMixin.parse_id_token() trusts nonce_supported in both authlib/integrations/base_client/sync_openid.py and authlib/integrations/base_client/async_openid.py to disable the expected nonce. 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/6563f6f7a8c2f71d2f85ee7511d72a4fbae3acPatch
- https://github.com/authlib/authlib/pull/949Patch
- https://github.com/authlib/authlib/releases/tag/v1.9.0Release Notes
- https://github.com/authlib/authlib/security/advisories/GHSA-c5mf-xmp2-59rcExploitVendor Advisory
FAQ
What is CVE-2026-114617?
CVE-2026-114617 is a vulnerability with a CVSS score of 4.2 (MEDIUM). Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, OpenIDMixin.parse_id_token() reads the nonce_supported decision from the untrusted ID token being validated a...
How severe is CVE-2026-114617?
CVE-2026-114617 has been rated MEDIUM with a CVSS base score of 4.2/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-114617?
Check the references section above for vendor advisories and patch information. Affected products include: Authlib Authlib.