SQL injection (SQLi) in MegaCMS v12.0.0, specifically in the “id_territorio” parameter of the “/web_comunications/cms/get_provincias” endpoint. The vulnerability arises from inadequate validation and sanitisation of user input. Specifically, via a POST request, the “id_territorio” parameter, used immediately after the registration form is submitted, could be manipulated by an unauthenticated attacker to execute arbitrary SQL queries.