CVE-2026-14631

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](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.

How to fix CVE-2026-14631

To remediate CVE-2026-14631, upgrade the affected package to a fixed version below.

• —upgrade to 5.2.6 or later

Is CVE-2026-14631 being exploited?

Low — EPSS is 0.3%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• from 0, < 5.2.6

CVSS scores

References (6)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-14631
• PATCHgithub.com/webpack/webpack-dev-server
• WEBcna.openjsf.org/security-advisories.html
• WEBgithub.com/webpack/webpack-dev-server/commit/f21ed0f44aceb6132abb591ee8b60d770b6e489f