Improper Validation of Specified Quantity in Input vulnerability in Tips and Tricks HQ WP Express Checkout (Accept PayPal Payments) allows Manipulating Hidden Fields.This issue affects WP Express Checkout (Accept PayPal Payments): from n/a through 2.3.7.
Solution:
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.