CVE-2026-6402

5.3 MEDIUM

webpack-dev-server versions up to and including 5.2.3 are vulnerable to cross-origin source code exposure when serving over a non-potenti...

Published: 2026-05-12 · Last updated: 2026-05-18

Severity and scoring

CVSS: 5.3 MEDIUM
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
CWE: CWE-749

Affected products

Vendor	Product
webpack.js	webpack-dev-server

Description

webpack-dev-server versions up to and including 5.2.3 are vulnerable to cross-origin source code exposure when serving over a non-potentially trustworthy origin such as plain HTTP. The previous fix relied on the Sec-Fetch-Mode and Sec-Fetch-Site request headers, which browsers omit for non-trustworthy origins, allowing a malicious site to load the bundled source as a script and read it across origins. Impact: an attacker controlling a website visited by a developer running webpack-dev-server can recover the application source code when the dev server runs over HTTP at a guessable host and port. Chromium based browsers from Chrome 142 onward are not affected due to local network access restrictions. Upgrade to webpack-dev-server 5.2.4 or later, which sets Cross-Origin-Resource-Policy: same-origin on responses.

Source: NVD

References

[NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-6402
[Vendor advisory]https://cna.openjsf.org/security-advisories.html
[Vendor advisory]https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78w

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