webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header
GHSA-m28w-2pqf-7qgj · CVE-2026-14631
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Description
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.
References
- WEB https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-m28w-2pqf-7qgj
- ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-14631
- WEB https://github.com/webpack/webpack-dev-server/pull/5699
- WEB https://github.com/webpack/webpack-dev-server/commit/f21ed0f44aceb6132abb591ee8b60d770b6e489f
- WEB https://cna.openjsf.org/security-advisories.html
- PACKAGE https://github.com/webpack/webpack-dev-server
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