CVE-2026-28498 - Vulnerability Analysis

Overview

Authlib Python library < 1.6.9 contains a broken authentication caused by fail-open hash verification logic for at_hash and c_hash claims in OpenID Connect ID Tokens, letting attackers bypass integrity checks by using unsupported alg values, exploit requires crafted forged ID Token.

Severity & Score

Impact

Attackers can bypass token integrity checks, potentially allowing unauthorized access or impersonation.

Mitigation

Upgrade to version 1.6.9 or later.

References

• https://github.com/authlib/authlib/commit/b9bb2b25bf8b7e01512d847a95c1749646eaa72b
• https://github.com/authlib/authlib/releases/tag/v1.6.9
• https://github.com/authlib/authlib/security/advisories/GHSA-m344-f55w-2m6j

Social Media Activity(1 post)

TheHackerWire

@thehackerwire

Mar 18, 2026

🟠 CVE-2026-28498 - High (7.5) 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. Specificall... 🔗 https://www.thehackerwire.com/vulnerability/CVE-2026-28498/ #CVE #vulnerability #infosec #cybersecurity #security #Tenda #patchstack

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