The Kaskade OAuth 2.0 Dynamic Client Registration Management implementation in Authlib has a security flaw where example code omits the critical check binding the registration_access_token to the specific client. This omission allows an attacker possessing any valid registration_access_token and knowledge of a client_id to bypass authorization and access, modify, or delete that client's registration. The vulnerability affects versions 4.0.4 and later. The CVSS 3.1 score is 8.8 (high severity).