Vite: Files outside `server.fs.allow` could be served when project paths match system paths on non-Windows machine

### Summary 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. ### Impact Only apps that meet all of the following conditions are affected: - explicitly expose the Vite dev server to the network (using `--host` or the [`server.host` option](https://vite.dev/config/server-options#server-host)) - contain an imported file whose root-relative browser URL is also the absolute path of a readable file on the host - The sensitive file is not matched by [`server.fs.deny`](https://vite.dev/config/server-options#server-fs-deny) - the dev server is not running on Windows ### Details When 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`. ### PoC The following example requires Linux with a readable `/etc/hostname`: ```bash $ mkdir vite-safe-module-path-poc $ cd vite-safe-module-path-poc $ npm init -y $ npm install [email protected] $ 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: ```bash $ 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 ```

Source published

21 Oct 2026 16:47:42 UTC

Source modified

21 Oct 2026 17:00:06 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Publisher rating · MODERATE