JavaScript Source Map Exposure

What is JavaScript Source Map Exposure?

Probes publicly accessible .map files for each detected JavaScript bundle. Source maps allow reconstruction of original, unminified source code.

This vulnerability class falls under the Input Validation phase of the OWASP Testing Guide (WSTG-CLNT). Security engineers prioritise input validation checks early in an assessment because weaknesses here provide a foothold that amplifies the severity of vulnerabilities found in later phases.

Security Impact

Exposed source maps hand attackers your application logic, API endpoints, and internal comments. They should never be reachable in production.

Left undetected, javascript source map exposure issues can persist unnoticed for months. Continuous automated scanning ensures your team receives an alert the moment a regression or new exposure is introduced — long before an attacker discovers it through manual enumeration or automated offensive tooling.

How DygDog Detects It

DygDog evaluates client-side security posture by examining Content Security Policies, DOM storage patterns, JavaScript library versions, and inter-origin communication channels.

The JavaScript Source Map Exposure check is implemented as a passive scan module, meaning it never sends dangerous payloads or modifies application state. Scans complete in approximately 3.0 s and run continuously in the background so your security posture reflects the current state of your site — not a point-in-time snapshot.

Remediation Approach

Deploy a restrictive Content Security Policy that eliminates unsafe-inline and unsafe-eval; keep third-party JavaScript dependencies updated and integrity-checked via SRI; and audit postMessage handlers for missing origin verification.

DygDog does not stop at detection. When a JavaScript Source Map Exposure finding is confirmed, the platform generates infrastructure-aware, copy-paste-ready remediation snippets using frontier AI models. Instead of generic advice you need to adapt, you receive code that targets your exact server, framework, and configuration.

OWASP References

This check maps to the following OWASP Testing Guide test cases:

• WSTG-CLNT-01View OWASP WSTG →

Related Input Validation Checks

These checks belong to the same testing phase and are often assessed together:

• JavaScript Security Analysis

  Scans for outdated libraries (jQuery, Angular, Lodash), dangerous patterns (eval), and exposed source maps.

• DOM-Based XSS Analysis

  Identifies DOM XSS sources (location, document.URL) and sinks (innerHTML, eval) in JavaScript code.

• Clickjacking Protection

  Verifies X-Frame-Options and CSP frame-ancestors protection against UI redressing attacks.

• WebSocket Security

  Detects WebSocket connections, checks for wss:// enforcement, and analyses handshake security.