Update the WordPress Easy Testimonial Slider and Form plugin to the latest available version (at least 1.0.16).
Nguyen Xuan Chien discovered and reported this Cross Site Scripting (XSS) vulnerability in WordPress Easy Testimonial Slider and Form Plugin. This could allow a malicious actor to inject malicious scripts, such as redirects, advertisements, and other HTML payloads into your website which will be executed when guests visit your site. This vulnerability has been fixed in version 1.0.16.