Multiple cross-site scripting (XSS) vulnerabilities in Dairy Farm Shop Management System Using PHP and MySQL v1.1 allow attackers to execute arbitrary web scripts and HTML via a crafted payload injected into the Category and Category Field parameters.
https://www.owasp.org/index.php/XSS_%28Cross_Site_Scripting%29_Prevention_Cheat_Sheet
https://www.acunetix.com/websitesecurity/cross-site-scripting/