Frontend User Notes <= 2.1.0 - Insecure Direct Object Reference to Authenticated (Subscriber+) Arbitrary Note Modification

The Frontend User Notes plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 2.1.0 via the 'funp_ajax_modify_notes' AJAX endpoint due to missing validation on a user controlled key. This makes it possible for authenticated attackers, with Subscriber-level access and above, to modify arbitrary notes that do not belong to them.