FluentCart < 1.6.5 - Unauthenticated Guest Customer Account Takeover via Checkout Email

The FluentCart A New Era of eCommerce WordPress plugin before 1.6.5 does not verify that the person placing a guest checkout controls the email address supplied, allowing unauthenticated attackers who know an existing guest customer's email to obtain a logged-in account bearing that address together with the customer's stored record.