CVE-2026-102266

A flaw was found in pyjwt. A remote attacker can forge authentication tokens and bypass security controls by signing tokens with an empty key. When verifying tokens against a JSON Web Key (JWK) set that contains an empty Hash-based Message Authentication Code (HMAC) key, the library fails to enforce key-length validation. This allows an attacker to generate valid tokens carrying arbitrary claims to gain unauthorized access.

This vulnerability is rated as having an Important impact for Red Hat products because successful exploitation allows an unauthenticated remote attacker to generate forged tokens with arbitrary administrative claims, completely bypassing authentication controls. The flaw is not classified as Critical because exploitation requires a specific misconfiguration prerequisite—the target environment must actively load a symmetric key set containing a blank key entry. Typical deployments running standard authentication configurations are not exposed unless an empty HMAC key definition is explicitly ingested by the application.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.