GHSA-vfpm-58rq-9qcg
Vite: First 4 bytes of files outside of `server.fs` setting is exposed by `?vite-wasm-instance`
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
### Summary
The first 4 bytes of files outside of `server.fs` setting can be returned to the browser by a request containing `?vite-wasm-instance`.
### Impact
Only apps that match one of the following conditions are affected:
- explicitly expose the Vite dev server to the network using `--host` or the [`server.host`](https://vite.dev/config/server-options#server-host) option
- there's a file that has a sensitive information in **the first 4 bytes**
- uses Node.js or Deno to run Vite (if Bun is used, it is not affected)
### Details
Requests containing the `?vite-wasm-instance` query are handled by the internal Wasm plugin's `load` hook. The hook removes the query and reads the resulting path directly from disk, but the `server.fs` checks were not applied.
After reading the file, Vite attempts to parse it as WebAssembly. When that parse fails, Node and deno throws an error that contains the first 4 bytes of the file.
### PoC
Create a denied file and start an affected Vite dev server:
```bash
echo 'SECRET_KEY=abc123\n' > .env
npm run dev
curl 'http://localhost:5173/.env?vite-wasm-instance'
```
This will show
```
Failed to parse WASM file "<root>/.env": WebAssembly.compile(): expected magic word 00 61 73 6d, found 53 45 43 52 @+0
```
References
External links from the advisory. They lead to third-party sites.
- https://github.com/vitejs/vite/security/advisories/GHSA-vfpm-58rq-9qcg
- https://nvd.nist.gov/vuln/detail/CVE-2026-112947
- https://github.com/vitejs/vite/pull/23655
- https://github.com/vitejs/vite/commit/b6c6d2fb3f853aab4092dc25f0d6816a96c23dff
- https://github.com/vitejs/vite/commit/ba8b7ab43b4afa5d0292ab4b6e3a7b5033cc9c73
- https://github.com/vitejs/vite