The WP Travel WordPress plugin before 12.0.2 does not properly verify that the requester owns the booking targeted by its bank-deposit slip submission, allowing an unauthenticated attacker who knows the target customer's email address to change that customer's booking payment state and attach a file to it.
https://wpscan.com/vulnerability/45ce8cd1-b365-4ea6-ac93-420c1c72ea4b/