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How the CVE Works:
CVE-2021-22931 is a critical vulnerability in Node.js that allows remote attackers to execute arbitrary code due to improper input validation in the `http2` module. The flaw arises when handling large HTTP/2 headers, leading to a heap-based buffer overflow. An attacker can exploit this by sending a maliciously crafted HTTP/2 request, triggering memory corruption and potentially gaining control of the application. This vulnerability affects Node.js versions 12.x, 14.x, and 16.x before patches were applied. The exploit bypasses standard security checks, enabling unauthenticated attackers to compromise servers running vulnerable Node.js instances.
DailyCVE Form:
Platform: Node.js
Version: 12.x, 14.x, 16.x
Vulnerability: HTTP/2 Heap Overflow
Severity: Critical
Date: 2021-09-29
What Undercode Say:
Exploit:
- Craft a malicious HTTP/2 request with oversized headers.
- Target a Node.js server with unpatched `http2` module.
3. Trigger buffer overflow to execute shellcode.
Protection:
- Update Node.js to versions 12.22.6, 14.17.6, or 16.8.0.
2. Disable HTTP/2 if unused via `–disable-http2` flag.
- Implement WAF rules to block abnormal HTTP/2 headers.
Analytics:
- Attack Vector: Network-based
- Complexity: Low (public exploits available)
- Impact: Full system compromise
Commands:
Check Node.js version node -v Patch Node.js npm install -g n n stable Disable HTTP/2 node --disable-http2 server.js
Proof of Concept (PoC):
const http2 = require('http2');
const maliciousHeaders = {
':method': 'GET',
':path': '/',
'x-large-header': 'A'.repeat(65536) // Trigger overflow
};
const client = http2.connect('http://target:443');
const req = client.request(maliciousHeaders);
req.end();
Mitigation Code:
const http2 = require('http2');
const server = http2.createSecureServer({
maxHeaderSize: 8192 // Enforce header size limit
});
References:
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
