Riaxe Product Customizer <= 2.1.2 - Unauthenticated Arbitrary User Deletion via 'user_id' Parameter

The Riaxe Product Customizer plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 2.1.2. This is due to the plugin registering a REST API route at POST /wp-json/InkXEProductDesignerLite/customer/delete_customer without a permission_callback, causing WordPress to default to allowing unauthenticated access, and the inkxe_delete_customer() callback function taking an array of user IDs from the request body and passing each one directly to wp_delete_user() without any authentication or authorization checks. This makes it possible for unauthenticated attackers to delete arbitrary WordPress user accounts, including administrator accounts, leading to complete site lockout and data loss.