CVE-2026-6402

5.3 MEDIUM 0.3% exploit odds Fix listed Other Browser & mail

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in, but needs a user to act. High risk of data exposure.
Exploit odds: 0.3% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-05-12 09:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 11:00 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.3% in the next 30 days (EPSS).
Severity: 5.3 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-05-12 09:16 UTC
Last modified: 2026-06-17 11:00 UTC
Exploit probability: 0.3% · EPSS, next 30 days
Weakness: CWE-749
Record status: Analyzed

Affected

webpack.js webpack-dev-server < 5.2.4

Attack profile CVSS 3.1 · 5.3

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-6402.md and follow it. Check whether this project is affected by CVE-2026-6402. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record