Vulnerability in webpack-dev-server (CVE-2026-14631)
Summary
Vulnerability in webpack-dev-server (CVE-2026-14631). Risk of unauthorized operations or information disclosure. Exploitable via Host. Mitigation: upgrade to 5.2.6 or later.
Original description
The description as published by the source.
Impact
An unauthenticated peer that can reach the webpack-dev-server process can terminate it by sending either a normal HTTP request with a malformed Host header, or a WebSocket upgrade to the default /ws endpoint with a malformed Origin header. The malformed header triggers an uncaught exception in the host-validation path and crashes the dev server process.
Patches
Fixed in webpack-dev-server 5.2.6 by treating malformed Host and Origin header values as invalid rather than throwing (see PR #5699).
Workarounds
Keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.
Source: NIST National Vulnerability Database 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-2026-14631 has been found in webpack-dev-server.
Attackers can target a specific entry point like Host over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade webpack-dev-server to 5.2.6 or later.
If unsure, ask your IT team or search "webpack-dev-server CVE-2026-14631" on the vendor's site.
CVE-2026-14631 (webpack-dev-server) — CWE-20 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Host / Origin / localhost
Patched: 5.2.6 — apply immediately
Workaround: Keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.
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.
A vulnerability (CWE-20) exists in webpack-dev-server. Attackers reach the vulnerable code path via Host without authentication.
Check the vendor advisory for the affected versions of webpack-dev-server. Attack surface: Host / Origin / localhost.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 5.2.6.
Workaround: Keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.
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
Concrete steps and command examples for SOC/SRE teams to execute in order
-
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。 -
2Apply temporary workaround mitigate
Keep the dev server bound to `localhost` (the default) and do not expose it to untrusted networks.パッチが適用されるまでの応急処置として、Keep the dev server bound to
localhost(the default) and do not expose it to untrusted networks. を実施。回避策の副作用 (機能低下) を確認した上で。 -
3Apply patch patch
Upgrade webpack-dev-server to 5.2.6ステージング環境で 5.2.6 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。
-
4Post-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
References
- web cna.openjsf.org
- web github.com
- web nvd.nist.gov
- web github.com
- web github.com
- web github.com