The Simply Schedule Appointments WordPress plugin before 1.6.12.11 does not perform a capability check on an administrative appointment-listing shortcode, and its per-user result scoping fails open for non-staff users, allowing users with the Contributor role and above to disclose all customers' appointment records, including names, email addresses, phone numbers and notes, across the whole site.
https://wpscan.com/vulnerability/551554a8-12fb-4eb5-bd24-ae627b58dc3b/