The WordPress Simple Shopping Cart plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 5.1.2 via the 'file_url' parameter. This makes it possible for unauthenticated attackers to view potentially sensitive information and download a digital product without paying for it.
https://www.tipsandtricks-hq.com/ecommerce/wp-simple-cart-sell-digital-downloads-2468
https://wordpress.org/plugins/wordpress-simple-paypal-shopping-cart/#developers