CVE-2026-112085
Undergoing Analysis
Undergoing Analysis - In Progress
WebSocket Proxy Bypass in webpack-dev-server
Vulnerability report for CVE-2026-112085, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-22
Last updated on: 2026-10-22
Assigner: openjs
Description
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| webpack-dev-server | webpack-dev-server | 0 |
| webpack-dev-server | webpack-dev-server | 6.0.0 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-1385 | The product uses a WebSocket, but it does not properly verify that the source of data or communication is valid. |
| CWE-346 | The product does not properly verify that the source of data or communication is valid. |
