WP Express Checkout (Accept PayPal Payments) <= 2.3.7 is vulnerable to Price Manipulation vulnerability

The WP Express Checkout (Accept PayPal Payments) plugin for WordPress is vulnerable to price manipulation in all versions up to, and including, 2.3.7. This is due to insufficient validation on the pricing data being passed to the server. This makes it possible for unauthenticated attackers to modify the price of bookings.