The Easy Appointments plugin for WordPress is vulnerable to unauthorized modification of data due to insufficient user validation on the ajax_cancel_appointment() function in all versions up to, and including, 3.11.18. This makes it possible for unauthenticated attackers to cancel other users orders.
The Easy Appointments plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'ea_full_calendar' shortcode in all versions up to, and including, 3.11.18 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.