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CVE-2026-112085— webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades

Quick assessment

Affected
webpack-dev-server webpack-dev-server
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

webpack-dev-server 是一个为 Webpack 项目提供实时重载功能的开发服务器。在 5.2.7 之前的版本以及 6.0.0 版本中，当代理配置项被设置为转发 WebSocket 时，服务器会将非热模块替换（HMR）的 WebSocket 升级请求直接转发至代理目标，而不会验证 Host 或 Origin 请求头，因此 allowedHosts 防护机制不适用于这些被代理的升级请求。攻击者可利用开发者访问的恶意网页，通过开发服务器建立跨源 WebSocket 连接，从而读取和写入被代理的后端服务，即

CVSS 8.2 · High EPSS 0.16% · P5

Affected Version Matrix 4

VendorProduct Version RangeStatus
webpack-dev-server webpack-dev-server < 5.2.7 affected
5.2.7 unaffected
6.0.0< 6.1.0 affected
6.1.0 unaffected
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I. Basic Information for CVE-2026-112085

Vulnerability Information
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Vulnerability Title
webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
源验证错误
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
webpack-dev-server webpack-dev-server 0 ~ 5.2.7 -

II. Public POCs for CVE-2026-112085

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III. Intelligence Information for CVE-2026-112085

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Vendor Advisories for CVE-2026-112085 (1)

IV. Related Vulnerabilities

Same product: webpack-dev-server
Same vendor: webpack-dev-server
Same weakness: CWE-346

V. Comments for CVE-2026-112085

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