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CVE-2026-6402
medium
CVSS 5.3
Vulnerability in webpack-dev-server (CVE-2026-6402)
Summary
vulnerability in webpack-dev-server (CVE-2026-6402). Confidential information can be exposed externally. Mitigation: upgrade to `5.2.4` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-6402** has been found in webpack-dev-server.
Confidential information can be exposed externally. CVSS score: 5.3/10.
What to do: upgrade webpack-dev-server to **5.2.4** or later.
If unsure, ask your IT team or search "webpack-dev-server CVE-2026-6402" on the vendor's site.
CVE-2026-6402 (webpack-dev-server) — CWE-749 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated
Patched: `5.2.4` — apply immediately
Workaround: Run the dev server with HTTPS enabled (`--https` or `server.type: 'https'` in config).
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-749) exists in webpack-dev-server.
📍 Affected scope
webpack-dev-server — .
🔥 Severity
Severity: Medium (CVSS 5.3/10). Confidential information can be exposed externally
🔧 How to fix
Update to **5.2.4**.
🛡️ Workaround
Workaround: Run the dev server with HTTPS enabled (`--https` or `server.type: 'https'` in config).
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'webpack-dev-server' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'webpack-dev-server' . | 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 `webpack-dev-server` を grep し、稼働しているサービス・バージョンを把握する。
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5Apply temporary workaround mitigate
Run the dev server with HTTPS enabled (`--https` or `server.type: 'https'` in config).パッチが適用されるまでの応急処置として、Run the dev server with HTTPS enabled (`--https` or `server.type: 'https'` in config). を実施。回避策の副作用 (機能低下) を確認した上で。
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6Apply patch patch
Upgrade webpack-dev-server to 5.2.4ステージング環境で 5.2.4 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
npm
webpack-dev-server
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.2.4"}]}]
References
- advisory https://nvd.nist.gov/vuln/detail/CVE-2026-6402
- package https://github.com/webpack/webpack-dev-server
- web https://cna.openjsf.org/security-advisories.html
- web https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78w
- web https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-4v9v-hfq4-rm2v
- web https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-9jgg-88mc-972h
- web https://github.com/advisories/GHSA-79cf-xcqc-c78w