Fluent Forms Pro Add On Pack <= 6.1.12 - Authenticated (Subscriber+) Server-Side Request Forgery via 'saveDataSource'

The Fluent Forms Pro Add On Pack plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 6.1.12 via the 'saveDataSource' function. This makes it possible for authenticated attackers, with Subscriber-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.