Cross-Site Scripting
Cross-Site Scripting (XSS) is a web security vulnerability that allows attackers to inject malicious client-side scripts into web pages viewed by other users. This occurs when an application includes untrusted data in a web page without proper validation or escaping, enabling the execution of scripts in the victim's browser. XSS attacks can lead to data theft, session hijacking, defacement, or malware distribution.
Developers should learn about XSS to build secure web applications and prevent common attacks that exploit user trust in a site. It's critical for roles involving web development, security engineering, or penetration testing, especially when handling user input, dynamic content, or third-party integrations. Understanding XSS helps implement defenses like input validation, output encoding, and Content Security Policy (CSP).