CVE-2025-30359 – Webpack-dev-server Cross-Site Scripting (XSS) and Prototype Pollution

CVE ID : CVE-2025-30359

Published : June 3, 2025, 6:15 p.m. | 14 minutes ago

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 they access a malicious web site. Because the request for classic script by a script tag is not subject to same origin policy, an attacker can inject a malicious script in their site and run the script. Note that the attacker has to know the port and the output entrypoint script path. Combined with prototype pollution, the attacker can get a reference to the webpack runtime variables. By using `Function::toString` against the values in `__webpack_modules__`, the attacker can get the source code. Version 5.2.1 contains a patch for the issue.

Severity: 5.3 | MEDIUM

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