source: https://www.securityfocus.com/bid/69815/info

The Wordfence Security Plugin for WordPress is prone to following vulnerabilities:

1. Multiple HTML-Injection vulnerabilities
2. Multiple Security Bypass vulnerabilities

Successful exploits of these issues allow the attacker-supplied HTML and script code to run in the context of the affected browser potentially allowing the attacker to steal cookie-based authentication credentials or control how the site is rendered to the user, or to bypass security mechanisms.

Wordfence Security Plugin 5.2.3 is vulnerable; other versions may also be affected

http://www.example.com/wp-admin/admin-ajax.php?action=revslider_show_image&img=../wp-config.php