Reflected Cross-Site Scripting (XSS) on the BeeTienda e-commerce platform, specifically in the latest demo version. The incident occurs due to a lack of proper sanitization of user input data in the 'search' parameter of the product list endpoint. When malicious payloads are transmitted via the 'search' parameter, they are displayed insecurely in the HTML response, allowing for the arbitrary execution of JavaScript code in the victim's browser.