eslint-plugin-browser-security

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

Description

This plugin provides Browser-specific security rules to prevent XSS and other client-side attacks.
By using this plugin, you can proactively identify and mitigate security risks across your entire codebase.

Philosophy

Interlace fosters strength through integration. Instead of stacking isolated rules, we interlace security directly into your workflow to create a resilient fabric of code. We believe tools should guide rather than gatekeep, providing educational feedback that strengthens the developer with every interaction.

Getting Started

- To check out the guide, visit eslint.interlace.tools. 📚
- 要查看中文指南, 请访问 eslint.interlace.tools. 📚
- 가이드 문서는 eslint.interlace.tools에서 확인하실 수 있습니다. 📚
- ガイドは eslint.interlace.toolsでご確認ください。 📚
- Para ver la guía, visita eslint.interlace.tools. 📚
- للاطلاع على الدليل، قم بزيارة eslint.interlace.tools. 📚

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

`💡 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

$3

`javascript // 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! });`

`$3`

`javascript // 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); });`

`⚙️ Configuration Presets`


| Preset        | Description                                         |
| :------------ | :-------------------------------------------------- |
|

recommended

 | Recommended security configuration                  |
|

strict

      | Strict security configuration - all rules as errors |
🤖 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.

`Rules`

Legend

| Icon | Description | | :---: | :--- | | 💼 | Recommended: Included in the recommended preset. | | ⚠️ | Warns: Set towarn in recommended preset. | | 🔧 | Auto-fixable: Automatically fixable by the--fixCLI option. | | 💡 | Suggestions: Providing code suggestions in IDE. | | 🚫 | Deprecated: This rule is deprecated. |

| Rule | CWE | OWASP | CVSS | Description | 💼 | ⚠️ | 🔧 | 💡 | 🚫 | | :--- | :---: | :---: | :---: | :--- | :---: | :---: | :---: | :---: | :---: | | detect-mixed-content | | | | ESLint rule documentation for detect-mixed-content | | | | | | | no-allow-arbitrary-loads | | | | ESLint rule documentation for no-allow-arbitrary-loads | | | | | | | no-clickjacking | | | | ESLint rule documentation for no-clickjacking | | | | | | | no-client-side-auth-logic | | | | ESLint rule documentation for no-client-side-auth-logic | | | | | | | no-cookie-auth-tokens | CWE-1004 | A02:2025 | 5.3 | ESLint rule documentation for no-cookie-auth-tokens | 💼 | | | 💡 | | | no-credentials-in-query-params | | | | ESLint rule documentation for no-credentials-in-query-params | | | | | | | no-disabled-certificate-validation | | | | ESLint rule documentation for no-disabled-certificate-validation | | | | | | | no-dynamic-service-worker-url | CWE-829 | A08:2025 | 7.5 | ESLint rule documentation for no-dynamic-service-worker-url | 💼 | | | 💡 | | | no-eval | CWE-95 | A03:2025 | 9.8 | ESLint rule documentation for no-eval | 💼 | | | 💡 | 🚫 | | no-filereader-innerhtml | CWE-79 | A03:2025 | 6.1 | ESLint rule documentation for no-filereader-innerhtml | 💼 | | | 💡 | | | no-http-urls | | | | ESLint rule documentation for no-http-urls | | | | | | | no-innerhtml | CWE-79 | A03:2025 | 6.1 | ESLint rule documentation for no-innerhtml | 💼 | | | 💡 | | | no-insecure-redirects | | | | ESLint rule documentation for no-insecure-redirects | | | | | | | no-insecure-websocket | | | | ESLint rule documentation for no-insecure-websocket | | | | | | | no-jwt-in-storage | CWE-922 | A02:2025 | 7.5 | ESLint rule documentation for no-jwt-in-storage | 💼 | | | 💡 | | | no-missing-cors-check | | | | ESLint rule documentation for no-missing-cors-check | | | | | | | no-missing-csrf-protection | | | | ESLint rule documentation for no-missing-csrf-protection | | | | | | | no-missing-security-headers | | | | ESLint rule documentation for no-missing-security-headers | | | | | | | no-password-in-url | | | | ESLint rule documentation for no-password-in-url | | | | | | | no-permissive-cors | | | | ESLint rule documentation for no-permissive-cors | | | | | | | no-postmessage-innerhtml | CWE-79 | A03:2025 | 6.1 | ESLint rule documentation for no-postmessage-innerhtml | 💼 | | | | | | no-postmessage-wildcard-origin | CWE-346 | A01:2025 | 8.8 | ESLint rule documentation for no-postmessage-wildcard-origin | 💼 | | | | | | no-sensitive-cookie-js | CWE-1004 | A02:2025 | 5.3 | ESLint rule documentation for no-sensitive-cookie-js | 💼 | | | 💡 | | | no-sensitive-data-in-analytics | | | | ESLint rule documentation for no-sensitive-data-in-analytics | | | | | | | no-sensitive-data-in-cache | | | | ESLint rule documentation for no-sensitive-data-in-cache | | | | | | | no-sensitive-indexeddb | CWE-922 | A02:2025 | 7.5 | ESLint rule documentation for no-sensitive-indexeddb | 💼 | | | 💡 | | | no-sensitive-localstorage | CWE-922 | A02:2025 | 7.5 | ESLint rule documentation for no-sensitive-localstorage | 💼 | | | 💡 | | | no-sensitive-sessionstorage | CWE-922 | A02:2025 | 7.5 | ESLint rule documentation for no-sensitive-sessionstorage | 💼 | | | 💡 | | | no-tracking-without-consent | | | | ESLint rule documentation for no-tracking-without-consent | | | | | | | no-unencrypted-transmission | | | | ESLint rule documentation for no-unencrypted-transmission | | | | | | | no-unescaped-url-parameter | | | | ESLint rule documentation for no-unescaped-url-parameter | | | | | | | no-unsafe-eval-csp | CWE-95 | A03:2025 | 9.8 | ESLint rule documentation for no-unsafe-eval-csp | 💼 | | | 💡 | | | no-unsafe-inline-csp | CWE-79 | A03:2025 | 6.1 | ESLint rule documentation for no-unsafe-inline-csp | 💼 | | | 💡 | | | no-unvalidated-deeplinks | | | | ESLint rule documentation for no-unvalidated-deeplinks | | | | | | | no-websocket-eval | CWE-95 | A03:2025 | 9.8 | ESLint rule documentation for no-websocket-eval | 💼 | | | 💡 | | | no-websocket-innerhtml | CWE-79 | A03:2025 | 6.1 | ESLint rule documentation for no-websocket-innerhtml | 💼 | | | 💡 | | | no-worker-message-innerhtml | CWE-79 | A03:2025 | 6.1 | ESLint rule documentation for no-worker-message-innerhtml | 💼 | | | | | | require-blob-url-revocation | CWE-401 | A04:2025 | 5.3 | ESLint rule documentation for require-blob-url-revocation | 💼 | ⚠️ | | 💡 | | | require-cookie-secure-attrs | CWE-614 | A05:2025 | 5.3 | ESLint rule documentation for require-cookie-secure-attrs | 💼 | | | | 🚫 | | require-csp-headers | | | | ESLint rule documentation for require-csp-headers | | | | | | | require-https-only | | | | ESLint rule documentation for require-https-only | | | | | | | require-mime-type-validation | | | | ESLint rule documentation for require-mime-type-validation | | | | | | | require-postmessage-origin-check | CWE-346 | A01:2025 | 8.8 | ESLint rule documentation for require-postmessage-origin-check | 💼 | | | | | | require-url-validation | | | | ESLint rule documentation for require-url-validation | | | | | | | require-websocket-wss | CWE-319 | A02:2025 | 7.5 | ESLint rule documentation for require-websocket-wss | 💼 | | | 💡 | 🚫 |

`🔗 Related ESLint Plugins`

Part of the Interlace ESLint Ecosystem — AI-native security plugins with LLM-optimized error messages:

📄 License

MIT © Ofri Peretz