User Profile Picture <= 2.6.1 - Authenticated (Author+) Insecure Direct Object Reference to Profile Picture Update

The User Profile Picture plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 2.6.1 via the 'rest_api_change_profile_image' function due to missing validation on a user controlled key. This makes it possible for authenticated attackers, with Author-level access and above, to update the profile picture of any user.