The Custom 404 Pro plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 3.7.1. This is due to missing or incorrect nonce validation on the custom_404_pro_admin_init function. This makes it possible for unauthenticated attackers to delete logs, via forged request granted they can trick a site administrator into performing an action such as clicking on a link.
https://www.wordfence.com/threat-intel/vulnerabilities/id/968920b9-febf-4d76-a16b-f27954cd72e5
https://plugins.trac.wordpress.org/browser/custom-404-pro/tags/3.7.1/admin/AdminClass.php#L114