In OpenStack Zaqar before 22.0.2, WSGI transport mishandles the URL-Signature header. By sending a request with an empty URL-Signature header, an unauthenticated remote attacker who knows a target project's UUID may bypass both Keystone authentication and pre-signed URL verification, resulting in the ability to read, enumerate, create, and delete that project's queues, messages, claims, and subscriptions. By additionally claiming an administrative role, the attacker may also perform administrative operations, such as managing pools and flavors in admin_mode deployments. Only deployments using the WSGI transport with an authentication strategy configured are affected; the websocket transport is not affected.