What is Cross-Site Scripting (XSS)? | UpGuard

## Executive Summary This document is an overview of Cross-Site Scripting (XSS) vulnerabilities that explains how XSS attacks operate (reflected, stored, DOM-based, Self-XSS, mutated), their potential impacts (session hijacking, data exposure, abuse of browser APIs), common attack vectors and example incidents, and recommended mitigations such as input sanitization, use of secure frameworks, Content Security Policy, and WAFs; it also includes promotional information about UpGuard's security assessment services.