REDHAT-BUG-2448164: High severity pypi/authlib vulnerability

Published Mar 16, 2026
·
Updated

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a JWK Header Injection vulnerability in authlib's JWS implementation allows an unauthenticated attacker to forge arbitrary JWT tokens that pass signature verification. When key=None is passed to any JWS deserialization function, the library extracts and uses the cryptographic key embedded in the attacker-controlled JWT jwk header field. An attacker can sign a token with their own private key, embed the matching public key in the header, and have the server accept the forged token as cryptographically valid — bypassing authentication and authorization entirely. This issue has been patched in version 1.6.9.

Affected Software

1 affected component
pypi/authlib<1.6.9

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade authlib to a version that resolves this vulnerability.

    Fixed in 1.6.9
  2. Configuration

    Update usage so that JWS deserialization functions do not receive key=None; provide the expected trusted verification key instead, since when key=None is passed authlib extracts and uses the cryptographic key from the attacker-controlled JWT JWK header.

    Authlib JWS deserialization key=None passed to JWS deserialization function = Do not pass key=None

Event History

Mar 16, 2026
Data Sourced
via Red Hat·06:02 PM
DescriptionSeverityAffected Software

Frequently Asked Questions

1

What is the severity of REDHAT-BUG-2448164?

The severity of REDHAT-BUG-2448164 is rated as high, with a score of 7.

2

How do I fix REDHAT-BUG-2448164?

To fix REDHAT-BUG-2448164, upgrade Authlib to version 1.6.9 or later.

3

What is affected by REDHAT-BUG-2448164?

REDHAT-BUG-2448164 specifically affects the Authlib Python library used for OAuth and OpenID Connect servers.

4

What impact does REDHAT-BUG-2448164 have on security?

The impact of REDHAT-BUG-2448164 allows an unauthenticated attacker to forge arbitrary JWT tokens that can pass signature verification.

5

Is there a workaround for REDHAT-BUG-2448164?

There is no official workaround for REDHAT-BUG-2448164 other than upgrading to the patched version.

Contact

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