The Easy Testimonials plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'testimonials_grid ' shortcode in all versions up to, and including, 3.9.5 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
https://plugins.trac.wordpress.org/browser/easy-testimonials/trunk/easy-testimonials.php#L1039