Featured Image from URL (FIFU) <= 5.3.1 - Authenticated (Contributor+) Server-Side Request Forgery via 'fifu_input_url'

The Featured Image from URL (FIFU) plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 5.3.1. This is due to insufficient validation of user-supplied URLs before passing them to the getimagesize() function in the Elementor widget integration. This makes it possible for authenticated attackers, with Contributor-level access and above, to make web requests to arbitrary locations originating from the web application and can be used to query and modify information from internal services via the fifu_input_url parameter in the FIFU Elementor widget granted they have permissions to use Elementor.