CVE-2026-14631: Webpack.js Webpack-Dev-Server

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Webpack.js Webpack-Dev-Server: before 5.2.6 (fixed in 5.2.6)

Published 2026-07-03. Last modified 2026-07-07.