p PatchFirst

CVE-2026-28802

CVE-2026-28802 · Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 7.7 · High · EPSS 0.6% · Fix available

Published
Updated

Stack: system · python

Affected products and versions

  • authlib

    Versions
    • >= 1.6.5, < 1.6.7: Affected

    No fix published

  • python-authlib Debian:13

    Versions
    • 1.6.0-1
    • 1.6.0-1+deb13u1
    • 1.6.1-1
    • 1.6.3-1
    • 1.6.4-1
    • 1.6.5-1
    • 1.6.6-1
    • 1.6.7-1
    • 1.6.8-1
    • 1.6.9-1
    • 1.7.0-1
    • 1.7.2-1
    • 1.7.2-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • python-authlib Debian:14

    Versions
    • 1.6.0-1
    • 1.6.1-1
    • 1.6.3-1
    • 1.6.4-1
    • 1.6.5-1
    • 1.6.6-1
    Affected ranges
    • ECOSYSTEM: < 1.6.7-1

    Update to 1.6.7-1

  • authlib PyPI

    Versions
    • 1.6.5
    • 1.6.6
    Affected ranges
    • ECOSYSTEM: ≥ 1.6.5, < 1.6.7

    Update to 1.6.7

  • python-authlib Ubuntu:25.10

    Versions
    • 1.5.1-1
    • 1.5.2-1
    • 1.6.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

Check your server →