Cross-site scripting (noun)

From the intrusion kill chain model, a malicious code delivery technique that allows hackers to send code of their choosing to their victim’s browser. XSS takes advantage of the fact that roughly 90% of web developers use the JavaScript scripting language to create dynamic content on their websites. Through various methods, hackers store their own malicious javascript code on unprotected websites. When the victim browses the site, the web server delivers that malicious code to the victim’s computer and the victim’s browser runs the code.