Nuxt dev server serves files from a parent directory with a stray lockfile or workspace file

Summary

Nuxt can pick a parent directory that does not declare a workspace as its default workspaceDir: the farthest directory with a lockfile when the project is not inside a git repository, or the farthest directory with a pnpm-workspace.yaml or deno.json file, even one that only holds settings. The Vite dev server allows /_nuxt/@fs/ requests for any file under workspaceDir. A stray lockfile or settings file in a parent directory, such as the home directory, therefore lets anyone who can reach the dev server read files in that directory and everything below it.

Impact

This affects the development server only; production builds are not affected. All of the following have to hold:

• A parent directory contains either:
  • a lockfile (package-lock.json, pnpm-lock.yaml, yarn.lock, bun.lock and similar), while the project is not inside a git repository and has no workspace file (pnpm-workspace.yaml, turbo.json, lerna.json and similar) above it. Running npm install once in the home directory is enough to create one there.
  • a pnpm-workspace.yaml without a packages list (for example one that only holds pnpm settings such as onlyBuiltDependencies), or a deno.json or deno.jsonc without a workspace field. This applies even if the project is inside a git repository.
• The dev server is reachable from the network (nuxt dev --host, nuxt dev --tunnel, a published container port, or a proxy onto the dev port). The default localhost bind limits this to local processes, which can usually read the same files directly.

For example, with ~/package-lock.json and a project at ~/projects/app that has no .git directory, nuxt dev --host serves GET /_nuxt/@fs/<home>/.ssh/id_ed25519 with status 200. Any file in the home directory that is not covered by Vite's server.fs.deny list can be read this way, including SSH keys, cloud credentials and the Nuxt DevTools auth token in ~/.nuxt/devtools/dev-auth-token.txt.

No browser is involved: a plain HTTP client is enough. A web page on another origin cannot read the response, and DNS rebinding is rejected by Vite's host check.

Projects whose parent directories contain none of these files are not affected, nor are projects inside a git repository whose only lockfile is their own. Nuxt 3.5.0 and later are affected.

Patches

Fixed in @nuxt/schema 4.6.4, which nuxt 4.6.4 depends on. A parent directory now only becomes the default workspaceDir if it declares a workspace: a pnpm-workspace.yaml with packages, a deno.json or deno.jsonc with workspace, a lerna.json, turbo.json or rush.json, a package.json with workspaces, or a git repository. A lockfile or a settings file alone no longer widens the dev server's server.fs.allow list. If your monorepo root is not detected this way, set workspaceDir in nuxt.config.ts. Nuxt 3 has reached end of life and will not receive a fix.

Workarounds

Set workspaceDir explicitly in nuxt.config.ts to the project root (or to the real monorepo root), or remove the stray lockfile or settings file from the parent directory. Do not expose the dev server to untrusted networks. If the dev port was reachable from an untrusted network while this layout was in place, treat files in the parent directory as exposed and rotate credentials such as SSH keys and cloud tokens.

Credits

Nuxt thanks @superboy-zjc for the report.