Origin Validation Error Affecting webpack-dev-server package, versions <5.2.7>=6.0.0 <6.1.0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-WEBPACKDEVSERVER-21431002
- published22 Oct 2026
- disclosed22 Oct 2026
- creditEurico Nicacio
Introduced: 22 Oct 2026
NewCVE-2026-112085 (opens in a new tab)How to fix?
Upgrade webpack-dev-server to version 5.2.7, 6.1.0 or higher.
Overview
webpack-dev-server is an Uses webpack with a development server that provides live reloading. It should be used for development only.
Affected versions of this package are vulnerable to Origin Validation Error via the WebSocket upgrade handler in lib/Server.js when a devServer.proxy entry is configured with ws: true. Upgrade requests are dispatched directly from the raw HTTP server and never enter the middleware chain, so allowedHosts and the cross-origin checks do not run for proxied WebSocket connections. An attacker can serve a cross-origin page that opens a WebSocket connection through the dev server proxy to a backend service the developer has configured, bypassing the Host and Origin header validation that protects the HMR socket.
Note: This is only exploitable when a devServer.proxy entry is configured with ws: true.