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A critical security vulnerability (CVE-2025-29927) has been identified in Next.js, affecting versions prior to 15.2.4. This flaw could allow attackers to exploit middleware subrequests, leading to potential server-side request forgery (SSRF) or denial-of-service (DoS) attacks.
Patch Your Next.js Application Immediately
To mitigate this risk, update your Next.js application using the following command:
npm audit fix --force
Ensure your application is running Next.js 15.2.4 or later.
### **Verify the Patch**
After updating, test the fix by sending a crafted request to your local server:
curl -v http://localhost:3000/ -H 'X-Middleware-Subrequest: middleware:middleware:middleware:middleware:middleware'
A successful patch should reject or sanitize malicious middleware subrequests.
You Should Know: Essential Security Practices for Next.js
### **1. Regular Dependency Audits**
Always check for vulnerabilities in your project dependencies:
npm audit
Automate security checks in CI/CD pipelines:
npm install -g npm-audit-ci npm-audit-ci --critical
### **2. Secure Middleware Configuration**
Avoid insecure middleware chaining. Use strict validation:
// middleware.js
export function middleware(request) {
if (request.headers.get('X-Middleware-Subrequest')?.includes('middleware')) {
return new Response('Blocked malicious request', { status: 403 });
}
}
### **3. Rate Limiting & DoS Protection**
Implement rate limiting using `express-rate-limit`:
npm install express-rate-limit
const rateLimit = require('express-rate-limit');
app.use(rateLimit({ windowMs: 15 * 60 * 1000, max: 100 }));
### **4. Enable Strict CSP Headers**
Add Content Security Policy (CSP) in `next.config.js`:
module.exports = {
async headers() {
return [{
source: '/(.*)',
headers: [{
key: 'Content-Security-Policy',
value: "default-src 'self'; script-src 'self' 'unsafe-inline'"
}]
}];
}
};
### **5. Monitor Suspicious Activity**
Use logging to detect attacks:
npm install morgan
const morgan = require('morgan');
app.use(morgan('combined'));
## **What Undercode Say**
Next.js remains a robust framework, but security misconfigurations can lead to severe breaches. Always:
– Patch immediately when CVEs are disclosed.
– Audit dependencies weekly.
– Harden middleware against injection.
– Enforce rate limits to prevent abuse.
– Log all requests for forensic analysis.
For advanced security, consider:
npx @next/security-check
And integrate **OWASP ZAP** for penetration testing:
docker run -v $(pwd):/zap/wrk -t owasp/zap2docker zap-baseline.py -t http://localhost:3000
### **Expected Output:**
- Next.js patched to v15.2.4+.
- Malicious middleware requests blocked.
- Security headers enforced.
- Logging and monitoring active.
Stay secure! 🔒
References:
Reported By: Activity 7310662812370882560 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
