ProSolution WP Client <= 2.0.8 - Unauthenticated Arbitrary File Deletion via 'newfilename' and 'filename' Parameters

The ProSolution WP Client plugin for WordPress is vulnerable to arbitrary file deletion due to insufficient file path validation in the proSol_fileDeleteProcess function in all versions up to, and including, 2.0.8. 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). An attacker must first call the proSol_fileUploadModalProcess handler to poison their own session with a path-traversal key, then call proSol_fileDeleteProcess with that key as the filename parameter; both steps require only the publicly exposed frontend nonce.