Simple Coherent Form <= 2.4.13 - Unauthenticated Arbitrary File Deletion via 'id' Parameter

Summary

The Simple Coherent Form plugin for WordPress is vulnerable to arbitrary file deletion due to insufficient file path validation in the removeUploadDir function in all versions up to, and including, 2.4.13. 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 scf_get_id_upload endpoint freely issues a valid scf_upload_file_removal nonce to any unauthenticated visitor, and the removal endpoint's secondary hash check is forgeable offline because it relies on a hardcoded salt embedded in the plugin source, meaning neither control presents a real authorization boundary.