PT-2026-39959 · Npm · Webpack-Dev-Server

Alexander Akait + 3 · Published 2026-05-12 · Updated 2026-05-18 · CVE-2026-6402

Positive Technologies (AI Summary)

CVSS v3.1

6.5

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions webpack-dev-server versions prior to 5.2.4

Description Cross-origin source code exposure occurs when serving over a non-potentially trustworthy origin, such as plain HTTP. The issue arises because the previous fix relied on Sec-Fetch-Mode and Sec-Fetch-Site request headers, which browsers omit for non-trustworthy origins. This allows a malicious site to load the bundled source as a script and read it across origins. An attacker controlling a website visited by a developer can recover the application source code if the 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.

Recommendations Upgrade to version 5.2.4 or later.

Fix

Weakness Enumeration

CWE-749

Related Identifiers

CVE-2026-6402

GHSA-79CF-XCQC-C78W

Affected Products

Webpack-Dev-Server

References · 10

• https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78w · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-6402 · Security Note
• https://cna.openjsf.org/security-advisories.html · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-79cf-xcqc-c78w · Vendor Advisory
• https://github.com/webpack/webpack-dev-server · Note
• https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-4v9v-hfq4-rm2v · Note
• https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-9jgg-88mc-972h · Note
• https://twitter.com/kom_256/status/2054107714595234215 · Twitter Post
• https://reddit.com/r/VulnMatter/comments/1tgqoye/resumen_diario_de_vulnerabilidades_18052026 · Reddit Post
• https://t.me/cveNotify/163869 · Telegram Post