Cross-Site Scripting (XSS)

Critical

Detects XSS vulnerabilities in web applications.

What It Checks

  • Unescaped user input in HTML output
  • DOM-based XSS in client-side code
  • Template literal injection in server-side rendering

Vulnerability Example

// Vulnerable res.send(`<h1>Hello, ${userName}</h1>`); // Safe const escapedName = escapeHtml(userName); res.send(`<h1>Hello, ${escapedName}</h1>`);

Severity

Critical - Can lead to session hijacking, defacement, or malware distribution.

Remediation

  1. Escape all user input before rendering
  2. Use Content Security Policy (CSP) headers
  3. Use templating engines with auto-escaping
  4. Validate and sanitize all input