The EventON WordPress plugin before 2.2.17 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Cross-Site Scripting attacks even when unfiltered_html is disallowed.
The EventON plugin for WordPress is vulnerable to Stored Cross-Site Scripting via admin settings in all versions up to, and including, 2.2.16 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.