The ImageRecycle pdf & image compression plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 3.1.14. This is due to missing or incorrect nonce validation on several functions in the class/class-image-otimizer.php file. This makes it possible for unauthenticated attackers to update plugin settings along with performing other actions via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.