Easy Appointments < 4.0.2.2 - Unauthenticated Appointment Cancellation/Confirmation via Forgeable Email-Link Token

Description

The plugin does not use an unguessable token to authorize its mail-link appointment cancellation and confirmation action, deriving the token from a hardcoded source-embedded salt and the appointment's creation timestamp, so unauthenticated attackers who know or guess that timestamp can cancel or confirm arbitrary appointments.