Python authlib: Prior to 1.9.0, OpenIDMixin.parse_id_token() reads the nonce_supported decision from the untrusted ID
Affects python-authlibSource GCVE Database
Not known to be exploited · CVSS 4.2 Medium · fixed in 1.9.0 : update python-authlib when convenient.
Data as of 28 Oct 2026, 22:31 UTC
- Patch
- Available – fixed in 1.9.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 22 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10python-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu Pro 26.04 LTSpython-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=esm-apps/resoluteOther threats | Affected
| Fixed in– |
Ubuntu Pro 24.04 LTSpython-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=esm-apps/nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSpython-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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.
References
- ubuntu.com/security/CVE-2026-114617 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-114617 (opens in a new tab)
- github.com/authlib/authlib/commit/6563f6f7a8c2f71d2f85ee7511d72a4fbae3acc0 (opens in a new tab)
- github.com/authlib/authlib/pull/949 (opens in a new tab)
- github.com/authlib/authlib/releases/tag/v1.9.0 (opens in a new tab)
- github.com/authlib/authlib/security/advisories/GHSA-c5mf-xmp2-59rc (opens in a new tab)