XLSXviewer <= 2.1.1 is vulnerable to Arbitrary File Deletion vulnerability

The XLSXviewer plugin for WordPress is vulnerable to arbitrary file deletion due to insufficient file path validation in all versions up to, and including, 2.1.1. This makes it possible for authenticated attackers, with Subscriber-level access and above, 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).