Affected: vitejs vite, vitejs vite-plus

Vite is a frontend tooling framework for JavaScript. From 6.0.0 to before 6.4.2, 7.3.2, and 8.0.5, the dev server’s handling of .map requests for optimized dependencies resolves file paths and calls readFile without restricting ../ segments in the URL. As a result, it is possible to bypass the server.fs.strict allow list and retrieve .map files located outside the project root, provided they can be parsed as valid source map JSON. This vulnerability is fixed in 6.4.2, 7.3.2, and 8.0.5.

Affected: npm: vite

### Summary

Any files ending with `.map` even out side the project can be returned to the browser.

### Impact

Only apps that match the following conditions are affected:

- explicitly exposes the Vite dev server to the network (using `--host` or [`server.host` config option](https://vitejs.dev/config/server-options.html#server-host)) - have a sensitive content in files ending with `.map` and the path is predictable

### Details

In Vite v7.3.1, the dev server’s handling of `.map` requests for optimized dependencies resolves file paths and calls `readFile` without restricting `../` segments in the URL. As a result, it is possible to bypass the [`server.fs.strict`](https://vite.dev/config/server-options#server-fs-strict) allow list and retrieve `.map` files located outside the project root, provided they can be parsed as valid source map JSON.

### PoC 1. Create a minimal PoC sourcemap outside the project root ```bash cat > /tmp/poc.map <<'EOF' {"version":3,"file":"x.js","sources":[],"names":[],"mappings":""} EOF ``` 2. Start the Vite dev server (example) ```bash pnpm -C playground/fs-serve dev --host 127.0.0.1 --port 18080 ``` 3. Confirm that direct `/@fs` access is blocked by `strict` (returns 403) <img width="4004" height="1038" alt="image" src="https://github.com/user-attachments/assets/15a859a8-1dc6-4105-8d58-80527c0dd9ab" /> 4. Inject `../` segments under the optimized deps `.map` URL prefix to reach `/tmp/poc.map` <img width="2…