Event Tickets and Registration < 5.26.6 - Unauthenticated Ticket Payment Bypass

Description

The Event Tickets and Registration plugin for WordPress is vulnerable to payment bypass in all versions up to, and including, 5.26.5. This is due to the /wp-json/tribe/tickets/v1/commerce/free/order endpoint not verifying that a ticket type should be free allowing the user to bypass the payment. This makes it possible for unauthenticated attackers to obtain access to paid tickets, without paying for them, causing a loss of revenue for the target.