The Simple Shopping Cart WordPress plugin before 5.3.3 does not verify submitted product prices against a value only the site owner can set, allowing users with the Contributor role and above to register attacker-chosen prices for existing products, which any visitor can then use to add those products to the cart at that price.

The Simple Shopping Cart WordPress plugin before 5.3.3 does not verify that a PayPal payment notification is for a payment received by the site owner's PayPal account in its default configuration, allowing unauthenticated attackers to have their orders marked as paid using a payment made to an account they control.