Is CVE-2026-28498 actively exploited?

No active exploitation of CVE-2026-28498 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-28498 be exploited remotely?

Yes. CVE-2026-28498 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-28498?

CVE-2026-28498 has a CVSS score of 7.5 (HIGH).

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HIGH

CVE-2026-28498

CWE-354Published: March 16, 2026· Updated: Mar 17, 2026

7.5

CVSS v3.1

EPSS:0.01%probability of exploitation in 30 daysPercentile:1.5th

Official Description

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.

NVD Source

Technical Analysis

CVE-2026-28498 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 7.5.