Vulnerability · Published Jun 3, 2025 · Assigned by GitHub_M
CVE-2025-30359webpack-dev-server users' source code may be stolen when they access a malicious web site
Medium 5.3
In plain English
A medium-severity security flaw in webpack-dev-server from webpack. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | webpack-dev-server | 5.2.1 | GHSA-4v9v-hfq4-rm2v |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| webpack | webpack-dev-server | < 5.2.1 |
Weakness: CWE-749 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N