3D Product configurator for WooCommerce <= 2.16.2 - Unauthenticated Remote Code Execution via 'xpv_image' Parameter

The 3D Product configurator for WooCommerce plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 2.16.2 via the 'xpv_image' parameter parameter. This is due to missing authentication and nonce checks on the wp_loaded handler combined with no sanitization of the xpv_image POST parameter before it is echoed unescaped into a Dompdf-rendered HTML template with PHP execution enabled. This makes it possible for unauthenticated attackers to execute code on the server. The only nonce and authentication check in the handler is entirely enclosed in a block comment with no replacement, making the endpoint reachable via a single unauthenticated POST to any URL on the site.