webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades
webpack-dev-server is a development server that provides live reloading for webpack projects. In versions before 5.2.7 and in version 6.0.0, when a proxy entry is configured to forward WebSockets, the server forwards non-HMR WebSocket upgrade requests to the proxy target without validating the Host or Origin headers, so the allowedHosts protection does not apply to those proxied upgrades. A malicious web page visited by a developer can open a cross-origin WebSocket through the dev server and read from and write to the proxied backend, even when the server is bound to loopback. The issue is fixed in webpack-dev-server 5.2.7 and 6.1.0, where proxied WebSocket upgrades pass the same Host and Origin validation as the HMR WebSocket, and users should upgrade to one of those versions or later. As a workaround, omit WebSocket forwarding from proxy entries that do not need it and scope the proxy to specific paths.
CVE-2026-112085
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-112085
webpack-dev-server
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "webpack-dev-server",
"product": "webpack-dev-server",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "5.2.7",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.2.7",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.0.0",
"lessThan": "6.1.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.0",
"versionType": "semver"
}
],
"packageURL": "pkg:npm/webpack-dev-server",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-112085
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #50240 · Revision 1
- Added to Heist Feed
- Publisher date