Advanced Product Fields (Product Addons) for WooCommerce < 1.6.22 - Unauthenticated Improper Input Validation to Price Bypass via Add-to-Cart POST Request

Description

The plugin is vulnerable to Improper Input Validation due to a logic flaw in the 'validate_cart_data' function. This makes it possible for unauthenticated attackers to bypass required paid addons and complete purchases at the base product price only, effectively stealing products by paying a fraction of the intended total. The vulnerability was partially patched in version 1.6.19.