Authlib: ID token can disable its own nonce validation via the nonce_supported claim (authlib authlib)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.27 % · percentile 19 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
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.
Weaknesses (CWE)
- CWE-294 — Authentication Bypass by Capture-replay
- CWE-807 — Reliance on Untrusted Inputs in a Security Decision
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 4.2 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N | GitHub_M |
| CVSS 3.1 | MEDIUM 4.2 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-c5mf-xmp2-59rc — Authlib: ID token can disable its own nonce validation via the nonce_supported claim
European references
- ENISA EUVD · EUVD-2026-108519
- GCVE · GCVE-0-2026-114617
Affected configurations (NVD CPE)
cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:*< 1.9.0
Affected products
| Product | Versions |
|---|---|
| authlib · authlib | affected < 1.9.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |