The WP Visitor Statistics (Real Time Traffic) WordPress plugin before 4.8 does not properly sanitise and escape the refUrl in the refDetails AJAX action, available to any authenticated user, which could allow users with a role as low as subscriber to perform SQL injection attacks
https://wpscan.com/vulnerability/7528aded-b8c9-4833-89d6-9cd7df3620de
https://plugins.trac.wordpress.org/changeset/2622268
http://packetstormsecurity.com/files/165433/WordPress-WP-Visitor-Statistics-4.7-SQL-Injection.html