CVE-2026-14631

MEDIUM 5.3

webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

webpack-dev-server versions 5.2.5 and earlier terminate the whole Node.js process when an unauthenticated peer sends 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 value causes an uncaught exception in the host-validation path and crashes the dev server. Impact is limited to availability of the development server, no data disclosure, no code execution. Patches: upgrade to webpack-dev-server 5.2.6. Workarounds: keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.

CWE	CWE-20 CWE-248
Vendor	webpack-dev-server
Product	webpack-dev-server
Published	Jul 3, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Scope

Confidentiality

Integrity

Availability

Affected Versions

webpack-dev-server / webpack-dev-server

0 < 5.2.6

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-m28w-2pqf-7qgj cna.openjsf.org: https://cna.openjsf.org/security-advisories.html

Credits

🔍 Str1ckl4nd bjohansebas UlisesGascon