Visma Pay for WooCommerce < 1.2.2 - Unauthenticated Payment Bypass and Order Data Disclosure via Gateway Return Endpoint

Description

The plugin does not verify the authenticity of payment gateway return requests, relying on a merchant secret that is empty on a store which has not entered its credentials, allowing unauthenticated attackers to mark arbitrary orders as paid and to disclose the name, email address and postal address of any order's customer.