Cross-Site Scripting (XSS): Attacks and Modern Defenses

Web applications face constant security threats, and Cross-Site Scripting remains one of the most prevalent vulnerabilities on the internet today. Understanding how attackers exploit these weaknesses is the first step toward building resilient, secure systems. Through this comprehensive written course, you will build a solid foundation in web security, learning to recognize vulnerable code patterns and implement modern defensive strategies to protect user data. What you'll learn: - Understand the core mechanics of Cross-Site Scripting and how attackers inject malicious scripts into trusted websites. - Analyze the key differences between Reflected, Stored, and DOM-based XSS vulnerabilities with clear code examples. - Apply robust input validation and contextual output encoding techniques to neutralize malicious payloads. - Configure modern security headers and Content Security Policy rules to mitigate XSS risks. - Leverage built-in security features in modern frontend frameworks to automatically escape untrusted data. - Practice identifying security flaws through written code analysis and conceptual exercises. You will start with essential web security definitions and browser execution models before moving into detailed breakdowns of different XSS types. The course concludes with comprehensive, practical defense strategies and written exercises to test your comprehension. This course is designed for beginner developers, aspiring security analysts, and technology enthusiasts with basic knowledge of HTML and JavaScript. No prior security experience is required. Start reading today to take your first step toward mastering web application security.