eslint-plugin-browser-security

⭐ If this plugin caught a real bug for you, star the repo — it's the signal that keeps these rules maintained.

Description

This plugin provides Browser-specific security rules to prevent XSS and other client-side attacks.

• Why — a linter nobody reads protects nothing. We would rather miss a finding than spend your attention on one that was never real.
• How — evidence, not names. A rule fires on what the code does, resolved through the AST and ESLint's own scope analysis.
• What — every finding carries its fix, in prose for a human and as structured JSON for an agent. Security rules add a CWE mapping and, where assigned, a CVSS score.

That trade costs recall, and we measure it: methodology · results · a false positive is a bug.

Getting Started

• To check out the guide, visit eslint.interlace.tools. 📚

npm install eslint-plugin-browser-security --save-dev

⚙️ Configuration Presets

🤖 LLM-Optimized Messages

All rules include structured remediation guidance designed for AI assistants:

[browser-security/no-innerhtml] XSS vulnerability: Direct HTML assignment detected.

📋 CONTEXT:
  • Pattern: element.innerHTML = unsanitizedInput
  • Risk: Any script in unsanitizedInput will execute

🛠️ REMEDIATION:
  Option A (Preferred): Use textContent for plain text
    element.textContent = userInput;

  Option B: Sanitize before insertion
    element.innerHTML = DOMPurify.sanitize(userInput);

📚 References:
  • CWE-79: https://cwe.mitre.org/data/definitions/79.html
  • OWASP XSS Prevention: https://owasp.org/...

By providing this structured context (CWE, OWASP, Fix), we enable AI tools to reason about the security flaw rather than hallucinating. This allows Copilot/Cursor to suggest the exact correct fix immediately.

💡 What You Get

• 21 security rules targeting browser-specific vulnerabilities
• XSS prevention via DOM manipulation and dynamic content detection
• Storage security preventing sensitive data exposure in localStorage/sessionStorage/IndexedDB
• Cross-origin protection with postMessage origin validation
• LLM-optimized messages with CWE references and auto-fix suggestions
• OWASP Top 10 coverage for browser security patterns

🎯 Why This Plugin?

Modern browser applications face unique security challenges across storage APIs, cross-origin communication, and dynamic content rendering. This plugin provides static analysis rules specifically designed for browser security patterns:

• XSS Prevention: Detects dangerous DOM manipulation patterns
• Storage Security: Prevents sensitive data exposure in localStorage/sessionStorage/IndexedDB
• Cross-Origin Protection: Validates postMessage origin checks
• Cookie Security: Identifies insecure cookie handling in JavaScript
• LLM-Optimized: All rules include AI-friendly remediation guidance

🔍 Detection Examples

❌ Vulnerable Code

// XSS via innerHTML
element.innerHTML = userInput;

// Code injection via eval
eval(dynamicCode);

// JWT in localStorage (XSS can steal it)
localStorage.setItem('token', jwt);

// postMessage without origin check
window.addEventListener('message', (event) => {
  processData(event.data); // Anyone can send messages!
});

✅ Secure Code

// Safe text assignment
element.textContent = userInput;

// Or sanitize before HTML insertion
element.innerHTML = DOMPurify.sanitize(userInput);

// Use HttpOnly cookies for auth tokens (set by server)
// Server: Set-Cookie: token=xxx; HttpOnly; Secure; SameSite=Strict

// Origin validation
window.addEventListener('message', (event) => {
  if (event.origin !== 'https://trusted-domain.com') return;
  processData(event.data);
});

📦 Compatibility

See the ESLint Version Support Policy — current ecosystem share data, the 20% gate, and the forward-looking exception that covers v10.

Rules

Legend

🔗 Related ESLint Plugins

Part of the Interlace ESLint ecosystem — AI-native rules with LLM-optimized error messages:

Security

Plugin	Downloads	Description
eslint-plugin-anthropic-security		Anthropic SDK security.
eslint-plugin-drizzle-security		Drizzle security.
eslint-plugin-express-security		Express middleware hardening.
eslint-plugin-gemini-security		Google Gemini SDK security.
eslint-plugin-jwt-security		Token security.
eslint-plugin-knex-security		Knex security.
eslint-plugin-lambda-security		AWS Lambda hardening.
eslint-plugin-mcp-sdk-security		MCP SDK security.
eslint-plugin-mongodb-security		MongoDB injection.
eslint-plugin-mysql-security		MySQL security.
eslint-plugin-nestjs-security		NestJS framework hardening.
eslint-plugin-node-security		Server-side patterns.
eslint-plugin-openai-security		OpenAI SDK security.
eslint-plugin-postgresql-security		PostgreSQL security.
eslint-plugin-prisma-security		Prisma security.
eslint-plugin-secure-coding		Injection prevention.
eslint-plugin-sequelize-security		Sequelize ORM security.
eslint-plugin-sqlite-security		SQLite security.
eslint-plugin-supabase-security		Supabase security.
eslint-plugin-typeorm-security		TypeORM security.
eslint-plugin-vercel-ai-security		AI SDK security.

Code quality

Plugin	Downloads	Description
eslint-plugin-cli-floor		CLI floor for commander, yargs and burgee.
eslint-plugin-conventions		Team-specific habits and styles.
eslint-plugin-import-next		Fast cycle + import-graph analysis.
eslint-plugin-maintainability		Cognitive load and clean-code patterns.
eslint-plugin-modernization		ESNext migration + syntax evolution.
eslint-plugin-modularity		Structural integrity and DDD patterns.
eslint-plugin-operability		Production readiness and resource health.
eslint-plugin-react-a11y		React accessibility / WCAG.
eslint-plugin-react-features		React best practices and optimization.
eslint-plugin-reliability		Runtime stability and error safety.

⭐ Support & follow

If this plugin caught a real bug for you, star the repo — stars are the signal that keeps the Interlace ESLint ecosystem maintained — and follow the writeups on Dev.to for the benchmarks and security research behind these rules.

📄 License

MIT © Ofri Peretz