CVE-2026-14631

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

State: Published
Severity: 5.3 Medium
Published: Jul 3, 2026
Updated: Jul 6, 2026
Reserved: Jul 3, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	5.3 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L	openjs

Weaknesses

CWE-20 Improper Input Validation
CWE-248 Uncaught Exception

Affected Products

Product	Versions
webpack-dev-serverwebpack-dev-server	before 5.2.6Affected 5.2.6Not affected

References

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