Vulnerability · Published Jul 3, 2026 · Assigned by openjs
CVE-2026-14631webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header
Medium 5.3
In plain English
A medium-severity improper input validation in webpack-dev-server from webpack-dev-server. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | webpack-dev-server | 5.2.6 | GHSA-m28w-2pqf-7qgj |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| webpack-dev-server | webpack-dev-server | 0 – before 5.2.6 |
Weakness: CWE-20, CWE-248 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L