The Direct Payments for WooCommerce WordPress plugin before 2.5.3 does not verify that the requester owns the targeted WooCommerce order in several unauthenticated AJAX handlers before changing its status and overwriting its payment metadata, allowing unauthenticated attackers to tamper with other customers' orders, including forging a "payment sent" state, overwriting the payment-method label, and attaching forged payment-proof files.