The WP Responsive Testimonials Slider And Widget WordPress plugin through 1.5 does not validate and escape some of its shortcode attributes before outputting them back in a page/post where the shortcode is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks
https://wpscan.com/vulnerability/7bdc1324-8d08-4185-971f-8d49367702cf