The Appointment Booking Plugin – LatePoint | Calendar & Scheduling for WordPress plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 5.6.9 via the set_customer_object due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to enumerate arbitrary customer records and disclose personally identifiable information - including first name, last name, email address, and phone number - by iterating the customer[id] parameter. This issue is exploitable only when the site is configured with customer authentication disabled (guest checkout enabled).