Tina is a headless content management system. Prior to 2.1.8 , the TinaCMS CLI dev server combines a permissive CORS configuration (Access-Control-Allow-Origin: *) with the path traversal vulnerability (previously reported) to enable a browser-based drive-by attack. A remote attacker can enumerate the filesystem, write arbitrary files, and delete arbitrary files on developer's machines by simply tricking them into visiting a malicious website while tinacms dev is running. This vulnerability is fixed in 2.1.8.

Affected: npm: @tinacms/cli

## Summary The TinaCMS CLI dev server combines a permissive CORS configuration (Access-Control-Allow-Origin: *) with the path traversal vulnerability (previously reported) to enable a browser-based drive-by attack. A remote attacker can enumerate the filesystem, write arbitrary files, and delete arbitrary files on developer's machines by simply tricking them into visiting a malicious website while tinacms dev is running.

## Details The TinaCMS dev server sets permissive CORS headers that allow **any origin** to make cross-origin requests:

- packages/@tinacms/cli/src/server/server.ts: ``` app.use(cors()); ```

- packages/@tinacms/cli/src/next/vite/plugins.ts: ``` server.middlewares.use(cors()); ``` When combined with the path traversal vulnerability, this creates a complete attack chain. ## Attack Scenario

### Prerequisites 1. Developer runs `tinacms dev` (default port 4001) 2. Developer visits attacker's website while TinaCMS is running

**No other conditions required** - the dev server doesn't need to be: - Exposed to the internet - Bound to 0.0.0.0 - Accessible outside localhost

### Attack Flow 1. Developer starts TinaCMS: `tinacms dev` 2. Developer browses the web (checking email, social media, etc.) 3. Developer unknowingly visits attacker-controlled page (malicious ad, compromised site, etc.) 4. Attacker's JavaScript exploits CORS + path traversal to read sensitive files 5. Files are exfiltrated to attacker's server

## PoC ### Attacker's Malicious Website (…