Static Code Analysis Tools

Static Application Security Testing (SAST) tools analyze source code to identify potential XSS vulnerabilities before deployment. Semgrep offers powerful pattern-matching capabilities with rules specifically designed for XSS detection. It supports multiple languages and can identify both simple vulnerabilities (like direct innerHTML usage with user input) and complex patterns that might lead to XSS. Semgrep's rule syntax allows creating custom patterns for organization-specific anti-patterns or frameworks.

ESLint with security plugins provides JavaScript-specific static analysis. Plugins like eslint-plugin-security and eslint-plugin-security-node flag potentially dangerous patterns such as innerHTML usage, eval() calls, or dangerouslySetInnerHTML in React. While these tools produce false positives (not every innerHTML usage is vulnerable), they help developers identify code requiring security review. Integrating ESLint into development workflows provides immediate feedback about potential security issues.

SonarQube, a comprehensive code quality platform, includes security rules for detecting XSS vulnerabilities across multiple languages. Its taint analysis tracks data flow from sources to sinks, identifying paths where user input might reach dangerous functions without sanitization. SonarQube's strength lies in its integration capabilities and detailed remediation guidance. The platform can track security debt over time and enforce quality gates that prevent vulnerable code from reaching production.