PayPlus Payment Gateway < 8.2.2 - Unauthenticated Order Key Disclosure and Order Status Modification

The PayPlus Payment Gateway WordPress plugin before 8.2.2 does not perform authorization or order-ownership validation in one of its AJAX actions available to unauthenticated users, allowing them to disclose the secret order key of arbitrary WooCommerce orders and, under some configurations, to modify order statuses.