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.

Classification

CVE ID: CVE-2025-30359

CVSS Base Severity: MEDIUM

CVSS Base Score: 5.3

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected Products

Vendor: webpack

Product: webpack-dev-server

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.03% (probability of being exploited)

EPSS Percentile: 7.25% (scored less or equal to compared to others)

EPSS Date: 2025-06-07 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: poc

SSVC Technical Impact: partial

SSVC Automatable: false

References

https://nvd.nist.gov/vuln/detail/CVE-2025-30359
https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-4v9v-hfq4-rm2v
https://github.com/webpack/webpack-dev-server/commit/d2575ad8dfed9207ed810b5ea0ccf465115a2239

Timeline