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TI-2026-79520 Aliases CVE-2026-114617GHSA-c5mf-xmp2-59rc

Authlib ID token can disable its own nonce validation

Priority LOW 19CWE-294Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
High
Impact type
Security bypass
Confidentiality · integrity · availability
Low · Low · None
Fix status
Partial Red Hat: 9 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-294.

Summary

Authlib before 1.9.0 is affected. OpenIDMixin.parse_id_token() trusts the nonce_supported claim in the untrusted ID token being validated, and a JSON false value disables the expected nonce (CWE-807). In implicit and hybrid relying parties, or applications that accept externally supplied ID tokens, an attacker with a captured validly signed token can replay it into an attacker-controlled session. Plain authorization code flow is not affected.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00265 18th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial authlib (authlib): 1.9.0authlib (PyPI): 1.9.0Red Hat: 9 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
authlibauthlibbefore 1.9.01.9.0Patch availableCNA
—authlib (PyPI)before 1.9.01.9.0Patch availableGHSA-c5mf-xmp2-59rc
  • authlib Vendorauthlib Affected before 1.9.0 Fixed in 1.9.0 Patch available CNA
  • authlib (PyPI) Vendor— Affected before 1.9.0 Fixed in 1.9.0 Patch available GHSA-c5mf-xmp2-59rc

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:*before 1.9.0Vulnerableauthlib
  • cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:* Versions before 1.9.0 Vulnerable ·authlib

Remediation

Upgrade Authlib to version 1.9.0. Red Hat rates the flaw Moderate and lists these products as affected without a fix: Exploit Intelligence (no fix planned), Red Hat Quay 3 (no fix planned), Lightspeed Core, Migration Toolkit for Applications 8, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux command line assistant, Red Hat OpenShift Virtualization 4 and Red Hat Satellite 6 (none available).

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA authlib (authlib) Fixed in 1.9.0
  • Fix · GHSA-c5mf-xmp2-59rc authlib (PyPI) Fixed in 1.9.0 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Exploit IntelligenceAffectedNo fix planned: Out of support scope
Lightspeed CoreAffectedNo fix yet: Fix deferred
Migration Toolkit for Applications 8AffectedNo fix yet: Fix deferred
OpenShift LightspeedAffectedNo fix yet: Fix deferred
Red Hat Ansible Automation Platform 2AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux command line assistantAffectedNo fix yet: Fix deferred
Red Hat OpenShift Virtualization 4AffectedNo fix yet: Fix deferred
Red Hat Quay 3AffectedNo fix planned: Out of support scope
Red Hat Satellite 6AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-23 Threatist record created from CVE-2026-114617
  2. 2026-10-23 Affected versions changed · Red Hat
  3. 2026-10-23 CVSS score added · Red Hat
  4. 2026-10-23 CISA SSVC decision points changed
  5. 2026-10-27 Alias added: GHSA-c5mf-xmp2-59rc

References

Exploit 1

Patch 2

Advisory 1

Other 2

  • TI-2026-22305 Authlib JWS JWK Header Injection: Signature Verification Bypass CVSS 3.1CRITICAL 9.1
  • TI-2026-79518 Authlib fix bypass lets attackers forge HS256 tokens with PEM keys CVSS 3.1CRITICAL 9.1
  • TI-2025-36973 Authlib: JWS/JWT accepts unknown crit headers (RFC violation → possible authz bypass) CVSS 3.1HIGH 7.5
  • TI-2024-25068 lepture Authlib before 1.3.1 has algorithm confusion with asymmetric public keys. CVSS 3.1HIGH 7.5
  • TI-2025-41738 Authlib: 1-click Account Takeover CVSS 3.1HIGH 8.8
  • TI-2026-22761 Authlib: Fail-Open Cryptographic Verification in OIDC Hash Binding CVSS 4.0HIGH 8.2
See all 18 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences