The Keap Official Opt-in Forms plugin for WordPress is vulnerable to Local File Inclusion in all versions up to, and including, 2.0.1 via the service parameter. This makes it possible for unauthenticated attackers to include PHP files on the server, allowing the execution of any PHP code in those files. This can be used to bypass access controls, obtain sensitive data, or achieve code execution in cases where PHP files can be uploaded and included. If register_argc_argv is enabled on the server and pearcmd.php is installed, this issue might lead to Remote Code Execution.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.