Headline

CVE-2021-32640

ws is an open source WebSocket client and server library for Node.js. A specially crafted value of the Sec-Websocket-Protocol header can be used to significantly slow down a ws server. The vulnerability has been fixed in [email protected] (https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff). In vulnerable versions of ws, the issue can be mitigated by reducing the maximum allowed length of the request headers using the --max-http-header-size=size and/or the maxHeaderSize options.

3 years ago

CVE

Open in Source

#vulnerability #web #nodejs #js #git

Impact

A specially crafted value of the Sec-Websocket-Protocol header can be used to significantly slow down a ws server.

Proof of concept

for (const length of [1000, 2000, 4000, 8000, 16000, 32000]) { const value = ‘b’ + ' '.repeat(length) + 'x’; const start = process.hrtime.bigint();

value.trim().split(/ *, */);

const end = process.hrtime.bigint();

console.log('length = %d, time = %f ns’, length, end - start); }

Patches

The vulnerability was fixed in [email protected] (00c425e) and backported to [email protected] (78c676d) and [email protected] (76d47c1).

Workarounds

In vulnerable versions of ws, the issue can be mitigated by reducing the maximum allowed length of the request headers using the --max-http-header-size=size and/or the maxHeaderSize options.

Credits

The vulnerability was responsibly disclosed along with a fix in private by Robert McLaughlin from University of California, Santa Barbara.

References