The Featured Image from URL (FIFU) WordPress plugin before 6.0.8, Featured Image from URL (FIFU) Premium WordPress plugin before 8.2.8 do not correctly enforce the REST API nonce, disabling the check for the whole request when a crafted URL is used, which could allow attackers to make a logged-in administrator perform any REST API action, such as creating a new administrator account, via a CSRF attack.
