CVE-2026-41479: Authlib

Medium severity, CVSS 5.4. EPSS: 0.3% chance of exploitation in the next 30 days.

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.6.10 and 1.7.1, Authlib's OAuth 2.0 authorization endpoint can be turned into an unauthenticated open redirect when a request uses an unsupported response_type and supplies an attacker-controlled redirect_uri. The vulnerable behavior happens before client lookup and before any redirect URI validation. As a result, an attacker does not need a valid client registration, an authenticated user, or any prior state. A single request to the authorization endpoint is enough to obtain a 302 Location response to an arbitrary attacker-controlled URL. This vulnerability is fixed in 1.6.10 and 1.7.1.

Affected products

• Authlib Authlib: before 1.6.10 (fixed in 1.6.10); version 1.7.0 only

Published 2026-06-22. Last modified 2026-06-26.