User Language Switch <= 1.6.10 - Authenticated (Administrator+) Server-Side Request Forgery via 'info_language' Parameter

The User Language Switch plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 1.6.10 due to missing URL validation on the 'download_language()' function. This makes it possible for authenticated attackers, with Administrator-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.