Car Seller - Auto Classifieds Script <= 2.1.0 - Unauthenticated SQL Injection

The request_list_request AJAX call of the Car Seller - Auto Classifieds Script WordPress plugin through 2.1.0, available to both authenticated and unauthenticated users, does not sanitise, validate or escape the order_id POST parameter before using it in a SQL statement, leading to a SQL Injection issue.