The gAppointments WordPress plugin through 1.9.5.1 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/e5664da4-5b78-4e42-be6b-e0d7b73a85b0