The WCFM Membership plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.9.10 due to missing nonce checks on various AJAX actions. This makes it possible for unauthenticated attackers to perform a wide variety of actions such as modifying membership details, changing renewal information, controlling membership approvals, and more, via a forged request granted they can trick a site's administrator into performing an action such as clicking on a link.