webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins
Impact
When webpack-dev-server is running on a non-HTTPS origin (the default), cross-origin requests from malicious websites can load the dev server's JavaScript bundles via <script> tags. The fix introduced in v5.2.1 (CVE-2025-30359) relied on Sec-Fetch-Mode and Sec-Fetch-Site request headers to block these requests, but browsers only send these headers for potentially trustworthy origins. Over plain HTTP, the headers are absent and the check is bypassed.
An attacker who knows the dev server's host, port, and output path can exfiltrate all module source code by intercepting the webpack runtime's module registration.
This does not affect Chrome 142+ (and other Chromium-based browsers) due to local network access restrictions.
Patches
Patched in webpack-dev-server >= 5.2.4 by setting Cross-Origin-Resource-Policy: same-origin on responses.
Workarounds
Run the dev server with HTTPS enabled (--https or server.type: 'https' in config).
Resources
- GHSA-4v9v-hfq4-rm2v (CVE-2025-30359) - original vulnerability
- GHSA-9jgg-88mc-972h (CVE-2025-30360) - prior bypass
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | webpack-dev-server | < 5.2.4 | 5.2.4 |
References
- https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-4v9v-hfq4-rm2v
- https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78w
- https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-9jgg-88mc-972h
- https://nvd.nist.gov/vuln/detail/CVE-2026-6402
- https://cna.openjsf.org/security-advisories.html
- https://github.com/webpack/webpack-dev-server
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N- Weakness (CWE)
CWE-749- Platform
- npm
- Package
webpack-dev-server- Disclosed
- 18.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-79cf-xcqc-c78w - CC BY 4.0
Vulnerability history: webpack-dev-server
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 7
- First → latest
- 01.2019 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 6
Disclosures per year
- 2019: 1
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 2
- 2026: 4
-
webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.