CVE-2026-28498

Published: Mar 16, 2026 Last Modified: Mar 16, 2026
ExploitDB:
Other exploit source:
Google Dorks:
HIGH 8,2
Source: [email protected]
Attack Vector: network
Attack Complexity: high
Privileges Required: none
User Interaction: none
Confidentiality: N/A
Integrity: N/A
Availability: N/A

Description

AI Translation Available

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a library-level vulnerability was identified in the Authlib Python library concerning the validation of OpenID Connect (OIDC) ID Tokens. Specifically, the internal hash verification logic (_verify_hash) responsible for validating the at_hash (Access Token Hash) and c_hash (Authorization Code Hash) claims exhibits a fail-open behavior when encountering an unsupported or unknown cryptographic algorithm. This flaw allows an attacker to bypass mandatory integrity protections by supplying a forged ID Token with a deliberately unrecognized alg header parameter. The library intercepts the unsupported state and silently returns True (validation passed), inherently violating fundamental cryptographic design principles and direct OIDC specifications. This issue has been patched in version 1.6.9.

354

Improper Validation of Integrity Check Value

Draft
Abstraction: Base Structure: Simple
Common Consequences
Security Scopes Affected:
Integrity Other Non-Repudiation
Potential Impacts:
Modify Application Data Other Hide Activities
Applicable Platforms
All platforms may be affected
Likelihood of Exploit: Medium
View CWE Details
573

Improper Following of Specification by Caller

Draft
Abstraction: Class Structure: Simple
Common Consequences
Security Scopes Affected:
Other
Potential Impacts:
Quality Degradation Varies By Context
Applicable Platforms
All platforms may be affected
View CWE Details
https://github.com/authlib/authlib/commit/b9bb2b25bf8b7e015…
https://github.com/authlib/authlib/commit/b9bb2b25bf8b7e01512d847a95c1749646eaa…
https://github.com/authlib/authlib/releases/tag/v1.6.9
https://github.com/authlib/authlib/releases/tag/v1.6.9
https://github.com/authlib/authlib/security/advisories/GHSA…
https://github.com/authlib/authlib/security/advisories/GHSA-m344-f55w-2m6j