The VikAppointments Services Booking Calendar plugin for WordPress is vulnerable to arbitrary file deletion due to insufficient file path validation in the extract function in all versions up to, and including, 1.2.21. 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). Exploitation requires at least one File-type custom field to be published on the confirmation page shortcode, as this field is not created by default during plugin installation.