The Responsive Lightbox & Gallery plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 2.7.1. This is due to the use of `strpos()` for substring-based hostname validation instead of strict host comparison in the `ajax_upload_image()` function. This makes it possible for authenticated attackers, with Author-level access and above, to make web requests to arbitrary locations originating from the web application, which can be used to query and modify information from internal services.

The Responsive Lightbox & Gallery plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 2.7.1. This is due to the use of `strpos()` for substring-based hostname validation instead of strict host comparison in the `ajax_upload_image()` function. This makes it possible for authenticated attackers, with Author-level access and above, to make web requests to arbitrary locations originating from the web application, which can be used to query and modify information from internal services.