CVE-2026-14631

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

CVSS 3.1 5.3 MEDIUMEUVD CVSS 3.1 5.3 CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary 5.3 MEDIUMCVSS_V3 Publisher rating MODERATEFixed by webpack-dev-server 5.2.6KEV status unknown

Original advisory

cve-program · CVE-2026-14631

Published

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.

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euvd · EUVD-2026-41559

Published

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nvd · CVE-2026-14631

Published

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osv · GHSA-m28w-2pqf-7qgj

Published

### 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](https://github.com/webpack/webpack-dev-server/pull/5699)). ### Workarounds Keep the dev server bound to `localhost` (the default) and do not expose it to untrusted networks.

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Affected versions, risk and source history

Exploitation and risk

Source status

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Risk history

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Advisory history

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15 Nov 2026 07:32:38 UTC