CVE-2026-6402

webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins

Published May 12, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-79cf-xcqc-c78w webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins
History
Type Values Removed Values Added
CPEs cpe:2.3:a:webpack.js:webpack-dev-server:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Webpack.js
Webpack.js webpack-dev-server
Vendors & Products Webpack.js
Webpack.js webpack-dev-server
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins
Weaknesses CWE-749
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
openjs
Published
Updated
May 12, 2026, 1:00 PM
Reserved
Apr 15, 2026, 8:35 PM
Status
Analyzed
Published
May 12, 2026, 9:16 AM
Modified
Nov 11, 2026, 8:10 PM
Severity
Moderate
Public date
May 12, 2026, 7:45 AM