Review reviewHigh

CVE-2026-28498

authlib authlib, Red Hat Ansible Automation Platform 2.6, Red Hat Quay 3.1

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...

CVSS: 8.2
EPSS: 0.23%
CISA KEV: Not listed
Published: 2026.03.17

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.23%

Technical severityCVSS 8.2

Vulnerability overview

Affected product and versions

Product: authlib authlib, Red Hat Ansible Automation Platform 2.6, Red Hat Quay 3.1
Affected versions: >= < 1.6.9, < 1.6.9
Fixed versions: 1.6.9

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that authlib authlib, Red Hat Ansible Automation Platform 2.6, Red Hat Quay 3.1 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE: CWE-325, CWE-354, CWE-573