Contact Form by Supsystic <= 1.7.24 - Cross-Site Request Forgery via AJAX action

The Contact Form by Supsystic plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.7.24. This is due to missing or incorrect nonce validation on the AJAX action handler. This makes it possible for unauthenticated attackers to execute AJAX actions via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.