The Notification WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/src/classes/Utils/Settings.php file which made it possible for attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 7.2.4. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.