p PatchFirst

CVE-2026-114615

CVE-2026-114615 · Authlib incomplete algorithm-confusion fix permits HMAC forgery with prefixed public keys

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 1.3.1 until 1.9.0, OctKey.import_key() checks asymmetric-key markers only at byte zero while Authlib's PEM loaders accept leading whitespace, comments, or a byte-order mark. In deployments that use the documented mixed algorithm registry and already configure verification with PEM or certificate bytes containing such a prefix, an unauthenticated attacker who knows those same public-key bytes can use them as an HMAC secret and forge HS256 tokens with arbitrary identity or authorization claims. This is a bypass of the remediation for CVE-2024-37568. The module-level jwt object reaches OctKey.import_key() in authlib/jose/rfc7518/oct_key.py, where POSSIBLE_UNSAFE_KEYS fails to identify prefixed asymmetric key material. This issue is fixed in version 1.9.0.

CVSS 7.4 · High · EPSS 0.1%

Published
Updated

Stack: system

Affected products and versions

  • authlib

    Versions
    • >= 1.3.1, < 1.9.0: Affected

    No fix published

  • python-authlib Debian:12

    Versions
    • 1.2.0-1
    • 1.2.0-1+deb12u1
    • 1.2.0-1+deb12u2
    • 1.2.1-1
    • 1.3.0-1
    • 1.3.0-2
    • 1.3.0-3
    • 1.3.1-1
    • 1.3.2-1
    • 1.3.2-2
    • 1.4.0-1
    • 1.4.1-1
    • 1.5.0-1
    • 1.5.1-1
    • 1.5.2-1
    • 1.6.0-1
    • 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: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
    • 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

Original sources

Check your server →