This report provides an overview of Cross-Site Scripting (XSS) vulnerabilities, a type of injection attack where malicious scripts are injected into trusted websites. It defines XSS, detailing how attackers inject code into web applications and deliver it to victims' browsers. The report discusses the impact of XSS on websites like Facebook and Twitter and outlines prevention methods such as validation, encoding, and testing. It explores XSS exploitation techniques, including session hijacking and phishing attacks, and suggests preventative measures like using automated code scanning tools, checking third-party packages for vulnerabilities, and conducting penetration tests. References to relevant research papers are also included to support the analysis of XSS vulnerabilities and their mitigation.