The Real Testimonials – Testimonial Slider, Collect Customer Reviews and Video Testimonials plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'tpro_client_testimonial' parameter in all versions up to, and including, 4.1.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Successful exploitation requires an administrator to approve the pending testimonial through standard moderation and the target page to load the WordPress Interactivity runtime (e.g. a theme or block that enqueues @wordpress/interactivity).