Rise0311

**Name of the Vulnerable Software and Affected Versions** Authlib versions prior to 1.6.10 Authlib versions prior to 1.7.1 **Description** Authlib's OAuth 2.0 authorization endpoint is susceptible to an unauthenticated open redirect. This occurs when a request utilizes an unsupported `response type` and provides an attacker-controlled `redirect uri`. The issue arises because the `get authorization grant()` function copies the raw `redirect uri` into an `UnsupportedResponseTypeError` before performing client lookup or redirect URI validation. Subsequently, the ` call ()` function in the base class automatically returns a 302 Location response to that URI. Consequently, an attacker can force the server to redirect to an arbitrary URL without needing a valid client registration, an authenticated user, or any prior state. **Recommendations** Update to version 1.6.10 or later. Update to version 1.7.1 or later.