Paytium: Mollie payment forms & donations <= 4.3.7 - Missing Authorization in 'pt_cancel_subscription'

The Paytium: Mollie payment forms & donations plugin for WordPress is vulnerable to unauthorized subscription cancellation due to a missing capability check on the pt_cancel_subscription function in versions up to, and including, 4.3.7. This makes it possible for authenticated attackers with subscriber-level access to cancel a subscription to the plugin.