The Age Gate plugin for WordPress is vulnerable to Local PHP File Inclusion in all versions up to, and including, 3.5.3 via the 'lang' parameter. This makes it possible for unauthenticated attackers to include and execute arbitrary PHP files on the server, allowing the execution of code in those files. This can be used to bypass access controls, obtain sensitive data, or achieve code execution in cases where images and other “safe” file types can be uploaded and included.