The Wava Payment Plugin WordPress plugin before 0.3.10 does not verify the authenticity of incoming payment-provider notifications, nor restrict who may send them, allowing unauthenticated attackers to change the status of any WooCommerce order in the store, including marking an unpaid order as paid and completed, and cancelling other customers' orders.
In versions up to 0.3.7 the response additionally returns the affected order's billing details, disclosing customer names, addresses, email addresses and phone numbers to the same unauthenticated caller.