What’s Vulnerable › Vulnerabilities

CVE-2025-30360: webpack-dev-server users' source code may be stolen when they access a malicious web site with non-Chromium based browser

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-06-03 · updated 2026-06-17
• Weakness: CWE-346

Description

webpack-dev-server allows users to use webpack with a development server that provides live reloading. Prior to version 5.2.1, webpack-dev-server users' source code may be stolen when you access a malicious web site with non-Chromium based browser. The `Origin` header is checked to prevent Cross-site WebSocket hijacking from happening, which was reported by CVE-2018-14732. But webpack-dev-server always allows IP address `Origin` headers. This allows websites that are served on IP addresses to connect WebSocket. An attacker can obtain source code via a method similar to that used to exploit CVE-2018-14732. Version 5.2.1 contains a patch for the issue.

Affected products

• webpack-dev-server: before 5.2.1 — fixed in 5.2.1
• Npm Webpack-Dev-Server: before 5.2.1 — fixed in 5.2.1

How to fix

Upgrade to a fixed version: webpack-dev-server 5.2.1; Npm Webpack-Dev-Server 5.2.1. Check the vendor advisory for mitigations.

References

• https://github.com/webpack/webpack-dev-server/blob/55220a800ba4e30dbde2d98785ecf4c80b32f711/lib/Server.js#L3113-L3127
• https://github.com/webpack/webpack-dev-server/commit/5c9378bb01276357d7af208a0856ca2163db188e
• https://github.com/webpack/webpack-dev-server/commit/72efaab83381a0e1c4914adf401cbd210b7de7eb
• https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-9jgg-88mc-972h

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