Package Instance

ws affected by a DoS when handling a request with many HTTP headers
A request with a number of headers exceeding the [`server.maxHeadersCount`][] threshold could be used to crash a ws server.

ws: Uninitialized memory disclosure
### Impact

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

### Proof of concept

```js
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 (https://github.com/websockets/ws/commit/c0327ec15a54d701eb6ccefaa8bef328cfc03086).

### Credits

Credit for the private and responsible disclosure of this issue goes to [Nikita Skovoroda](https://github.com/ChALkeR).

### 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

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

Improper Restriction of Operations within the Bounds of a Memory Buffer
A vulnerability was found in the ping functionality of the ws module before 1.0.0 which allowed clients to allocate memory by sending a ping frame. The ping functionality by default responds with a pong frame and the previously given payload of the ping frame. This is exactly what you expect, but internally ws always transforms all data that we need to send to a Buffer instance and that is where the vulnerability existed. ws didn't do any checks for the type of data it was sending. With buffers in node when you allocate it when a number instead of a string it will allocate the amount of bytes.

Improper Input Validation
ws is a "simple to use, blazing fast and thoroughly tested websocket client, server and console for node.js, up-to-date against RFC-6455". By sending an overly long websocket payload to a `ws` server, it is possible to crash the node process. This affects ws 1.1.0 and earlier.

Uncontrolled Resource Consumption
ws is an open source WebSocket client and server library for Node. In vulnerable versions of ws, the issue can be mitigated by reducing the maximum allowed length of the request headers.