Source Map Exposure
Last updated: January 12, 2026
Source map exposure occurs when production builds include source maps, allowing anyone to view your original, unminified source code.
Scan for This VulnerabilityWhat is Source Map Exposure?
Source maps are debugging files that map minified code back to original source. While useful in development, exposing them in production reveals your entire codebase, including business logic, API endpoints, internal comments, and potentially secrets that weren't properly removed.
Why It's Dangerous
This vulnerability can allow attackers to access sensitive data, compromise user accounts, or gain unauthorized control over your application. In AI-generated code, this issue is particularly common because security measures are often deprioritized in favor of rapid feature development.
Why AI Code Is Vulnerable
AI code generation tools focus on producing functional code quickly. They often generate patterns that work correctly but lack the defensive measures experienced security engineers would implement. This makes source map exposure particularly prevalent in vibe-coded applications.
Understanding the Technical Details
Source Map Exposure is classified as a medium-severity vulnerability because of its potential to cause significant damage to your application and users. Understanding the technical mechanics helps you recognize and prevent this issue in your own code.
This vulnerability typically occurs when security controls are either missing entirely, improperly configured, or incorrectly implemented. In many cases, the code appears to work correctly during development and testing, but the security flaw becomes exploitable once the application is deployed and accessible to malicious actors.
Attackers actively scan for this type of vulnerability using automated tools. Once discovered, exploitation can be rapid—often within hours of your application going live. The consequences range from data theft and account takeover to complete system compromise depending on the application's architecture.
For vibe-coded applications built with platforms like Lovable, Bolt.new, Replit, or v0.dev, this vulnerability appears in roughly 20-40% of deployments according to security research. The AI-generated patterns often follow insecure defaults that require manual security hardening.
How It Happens
- Production build configured to include source maps
- Source maps uploaded to hosting platform
- Default build settings not changed
- Debugging enabled in production
Impact
Business logic exposed to competitors
Internal API endpoints revealed
Comments and documentation visible
Potential secrets found in code
Easier vulnerability discovery for attackers
How to Detect
- Check for .map files in network requests
- Look for sourceMappingURL comments in JS files
- Try accessing /filename.js.map directly
- Run VAS to detect source map exposure
How to Fix
Disable source maps in production
Configure your build to not generate source maps.
// next.config.js
module.exports = {
productionBrowserSourceMaps: false,
}
// vite.config.js
export default {
build: {
sourcemap: false,
},
}Remove existing source maps
Delete any .map files from your production deployment.
Configure hosting to block .map files
Add rules to prevent source map access even if uploaded.
# _headers (Netlify) or similar
/*.map
X-Robots-Tag: noindex
# Or return 404 for .map filesCommonly Affected Platforms
Prevention Best Practices
The most effective approach to source map exposure is prevention. Implementing security measures during development is significantly easier and less costly than remediating vulnerabilities after deployment.
Security-First Development
When using AI code generation tools, always review the generated code for security implications. AI tools prioritize functionality over security, so treat all generated code as requiring security review. Establish a checklist of security requirements specific to your application type and verify each before deployment.
Continuous Security Testing
Integrate security scanning into your development workflow. Run scans after major code changes, before deployments, and on a regular schedule for production applications. Early detection of vulnerabilities reduces remediation costs and prevents potential breaches.
Defense in Depth
Never rely on a single security control. Implement multiple layers of protection so that if one control fails, others still protect your application. For example, combine authentication, authorization, input validation, and output encoding to create comprehensive protection against attacks.
Stay Informed
Security threats evolve constantly. Follow security researchers, subscribe to vulnerability databases, and monitor your dependencies for known issues. Understanding emerging threats helps you proactively protect your applications before attackers exploit new techniques.
Is Your App Vulnerable?
VAS automatically scans for source map exposure and provides detailed remediation guidance with code examples. Our scanner specifically targets vulnerabilities common in AI-generated applications.
Scans from $5, results in minutes. Get actionable results with step-by-step fix instructions tailored to your stack.
Get Starter ScanFrequently Asked Questions
Are source maps really a security risk?
Yes, but the severity varies. Source maps reveal: original variable/function names, code comments (which might contain TODOs with security notes), API endpoint structures, and business logic. They don't expose server-side secrets, but they make it easier for attackers to understand and exploit your client-side code.
How do I check if source maps are exposed?
Open browser DevTools > Sources tab. If you see your original source files (with original names, not minified), source maps are exposed. Or check directly: try accessing your-site.com/path/to/bundle.js.map - if it downloads, it's exposed.
Can I use source maps for error tracking without exposing them?
Yes! Upload source maps to your error tracking service (Sentry, Bugsnag, LogRocket) but don't deploy them publicly. Configure your build to generate source maps, upload them to the service, then delete before deploy. This gives you readable stack traces without public exposure.
What's the difference between hidden and inline source maps?
Inline source maps embed the map data in the JS bundle itself (always exposed). 'Hidden' source maps (webpack devtool: 'hidden-source-map') generate external .map files without the //# sourceMappingURL comment - browsers won't load them, but they're still accessible if you know the URL.