The Simply Schedule Appointments WordPress plugin before 1.5.7.7 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)

The Simply Schedule Appointments WordPress plugin before 1.5.7.7 is missing authorisation in a REST endpoint, allowing unauthenticated users to retrieve WordPress users details such as name and email address