Authlib: ID token can disable its own nonce validation via the nonce_supported claim

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-114617
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-22 22:18:04 UTC
Updated2026-10-22 22:18:04 UTC
DescriptionAuthlib 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.

Risk And Classification

Primary CVSS: v3.1 4.2 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Problem Types: CWE-294 | CWE-807 | CWE-294 CWE-294: Authentication Bypass by Capture-replay | CWE-807 CWE-807: Reliance on Untrusted Inputs in a Security Decision

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.2MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
3.1CNADECLARED4.2MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Authlib Authlib affected < 1.9.0 Not specified

References

ReferenceSourceLinkTags
github.com/authlib/authlib/pull/949 [email protected] github.com
github.com/authlib/authlib/security/advisories/GHSA-c5mf-xmp2-59rc [email protected] github.com
github.com/authlib/authlib/releases/tag/v1.9.0 [email protected] github.com
github.com/authlib/authlib/commit/6563f6f7a8c2f71d2f85ee7511d72a4fbae3acc0 [email protected] github.com
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