CVE-2026-73222

### Summary `npx claude-code-templates --studio` launches "Claude Code Studio", an Express HTTP server (`cli-tool/src/sandbox-server.js`, default port 3444) that binds to **all interfaces** (`0.0.0.0`), sets `Access-Control-Allow-Origin: *`, and requires **no authentication**. Two POST endpoints pass attacker-controlled request-body fields into `child_process.spawn(..., { shell: true })`. Because `shell: true` makes Node join the argv array into a single `sh -c` string, the fields are parsed by the shell and metacharacters execute. Any unauthenticated attacker who can reach the port — a malicious web page the developer visits, or anyone on the same LAN — can execute arbitrary OS commands on the developer's machine. ### Details In `cli-tool/src/sandbox-server.js`: - `app.listen(PORT, ...)` is called with no host argument, so the server listens on `0.0.0.0` / `::` (reachable from the LAN, not just localhost). - The CORS middleware sends `Access-Control-Allow-Origin: *` and answers the preflight `OPTIONS` for any origin, so a browser will deliver cross-origin POSTs to it. - There is no authentication on any endpoint. The vulnerable sinks: 1. `POST /api/execute` — the `prompt` body field flows into `executeLocalTask()`: ```js const child = spawn('claude', [finalPrompt], { /* ... */ shell: true }); The only validation on prompt is a length check (>= 10 chars). With shell: true, finalPrompt is interpreted by the shell. 2. POST /api/install-agent — the agentName body field: const child = spawn('npx', ['claude-code-templates@latest', '--agent', agentName, '--yes'], { /* ... */ shell: true }); 2. agentName is used unvalidated. (The same unsafe pattern is also reachable through /api/execute's agent field via checkAndInstallAgent().) Root cause: spawn(cmd, argsArray, { shell: true }) does not keep argsArray as separate argv entries — Node builds cmd + ' ' + argsArray.join(' ') and runs it via sh -c, so every element is subject to shell parsing. PoC # Victim np