The Salon Booking System, Appointment Scheduling for Salons, Spas & Small Businesses WordPress plugin before 1.9.4 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
https://wpscan.com/vulnerability/7f7667fd-6ac6-4c90-aaf0-c7862bd8e9bd/