The Everest Forms (Pro) plugin for WordPress is vulnerable to arbitrary file deletion due to insufficient file path validation in the delete_entry_files() function in all versions up to, and including, 1.9.4. This makes it possible for unauthenticated attackers to delete arbitrary files on the server, which can easily lead to remote code execution when the right file is deleted (such as wp-config.php). The vulnerability requires an admin to trigger the deletion via deletion of a form entry and cannot be carried out by the attacker alone.
The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize absolute path sequences such as “/abs/path” that can resolve to a location that is outside of that directory.