Missing Security Headers
Last updated: January 12, 2026
Security headers are HTTP response headers that protect against common web attacks like XSS, clickjacking, and man-in-the-middle attacks.
Scan for This VulnerabilityWhat is Missing Security Headers?
Modern browsers support several security headers that provide defense-in-depth against web attacks. Without these headers, your application relies solely on code-level defenses, which may have gaps. Headers like CSP prevent XSS, X-Frame-Options prevents clickjacking, and HSTS ensures HTTPS is used.
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 missing security headers particularly prevalent in vibe-coded applications.
Understanding the Technical Details
Missing Security Headers is classified as a high-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
- Default hosting configurations don't include security headers
- Developers unaware of header importance
- Headers not configured in framework or hosting platform
- Headers removed during deployment process
Impact
Cross-Site Scripting (XSS) attacks may succeed
Clickjacking attacks can trick users
Man-in-the-middle attacks on non-HTTPS connections
Browser feature abuse (camera, microphone access)
Reduced security audit scores
How to Detect
- Check response headers in browser DevTools > Network tab
- Use online security header checkers
- Run VAS to analyze your header configuration
- Use curl -I https://yoursite.com to see headers
How to Fix
Add Content-Security-Policy
CSP prevents XSS by controlling which scripts can execute.
// next.config.js
headers: [
{
key: 'Content-Security-Policy',
value: "default-src 'self'; script-src 'self' 'unsafe-inline'"
}
]Add X-Frame-Options
Prevents your site from being embedded in iframes (clickjacking protection).
{
key: 'X-Frame-Options',
value: 'DENY'
}Enable HSTS
Forces browsers to only use HTTPS connections.
{
key: 'Strict-Transport-Security',
value: 'max-age=31536000; includeSubDomains'
}Add other recommended headers
Include additional security headers for defense in depth.
{
key: 'X-Content-Type-Options',
value: 'nosniff'
},
{
key: 'Referrer-Policy',
value: 'strict-origin-when-cross-origin'
}Commonly Affected Platforms
Prevention Best Practices
The most effective approach to missing security headers 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 missing security headers 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
Which security headers are most important?
In order of priority: 1) Content-Security-Policy (prevents XSS), 2) Strict-Transport-Security (forces HTTPS), 3) X-Frame-Options (prevents clickjacking), 4) X-Content-Type-Options (prevents MIME sniffing). Start with these four, then add Referrer-Policy and Permissions-Policy.
Why does CSP break my site?
CSP blocks resources not in your allowlist. Common issues: inline scripts need 'unsafe-inline' or nonces, external scripts need their domain added, Google Fonts needs fonts.googleapis.com and fonts.gstatic.com. Start with 'Content-Security-Policy-Report-Only' to test without breaking your site.
Where do I configure security headers?
Depends on your hosting: Vercel uses next.config.js or vercel.json, Netlify uses _headers file, Cloudflare uses Page Rules or Workers, nginx uses add_header directive. For Next.js apps, next.config.js headers() function is recommended.
Do security headers replace proper coding practices?
No, headers are defense-in-depth, not a replacement. CSP provides a safety net if XSS slips through your code sanitization. Use both: write secure code AND configure security headers. Headers catch mistakes your code review missed.