CVE-2026-6402webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins
Updated under an hour ago ()
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It affects webpack-dev-server and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
- Weakness (CWE)
- CWE-749
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- openjs
- NVD analysis
- Analyzed
- Record last updated
- May 12, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
webpack-dev-server webpack-dev-server webpack_dev_server:webpack_dev_server (from the name) | before 5.2.4; 5.2.4 not affected | CNA record |
webpack.js webpack-dev-server webpack.js:webpack-dev-server | before 5.2.4 | NVD |
References
- https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78wmitigation, vendor-advisory
- https://cna.openjsf.org/security-advisories.htmlvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.