CVE-2026-28802: Authlib

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.

Affected products

• Authlib Authlib: from 1.6.5, before 1.6.7 (fixed in 1.6.7)

Published 2026-03-06. Last modified 2026-09-10.