CVE-2026-73222: Claude Code Templates Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-79wm-x847-7cvg",
  "modified" : "2026-09-03T19:50:47Z",
  "published" : "2026-09-03T19:50:47Z",
  "aliases" : [ "CVE-2026-73222" ],
  "summary" : "Claude Code Templates: Unauthenticated OS command injection (RCE) in Claude Code Studio server (--studio)",
  "details" : "### Summary\n`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.\n\n### Details\nIn `cli-tool/src/sandbox-server.js`:\n\n- `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).\n- 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.\n- There is no authentication on any endpoint.\n\nThe vulnerable sinks:\n\n1. `POST /api/execute` — the `prompt` body field flows into `executeLocalTask()`:\n   ```js\n   const child = spawn('claude', [finalPrompt], { /* ... */ shell: true });\n   The only validation on prompt is a length check (>= 10 chars). With shell: true, finalPrompt is interpreted by the shell.\n\n2. POST /api/install-agent — the agentName body field:\nconst child = spawn('npx', ['claude-code-templates@latest', '--agent', agentName, '--yes'], { /* ... */ shell: true });\n2. agentName is used unvalidated. (The same unsafe pattern is also reachable through /api/execute's agent field via checkAndInstallAgent().)\n\nRoot 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.\n\nPoC\n\n# Victim\nnpx claude-code-templates --studio          # server on 0.0.0.0:3444\n\n# Attacker (another LAN host, or a malicious web page fetch(), or locally)\ncurl -s -X POST http://127.0.0.1:3444/api/execute \\\n  -H 'Content-Type: application/json' \\\n  --data '{\"prompt\":\"aaaaaaaaaa; touch /tmp/CCT_RCE_PROOF\",\"mode\":\"local\"}'\n\ncurl -s -X POST http://127.0.0.1:3444/api/install-agent \\\n  -H 'Content-Type: application/json' \\\n  --data '{\"agentName\":\"x; touch /tmp/CCT_AGENT_PROOF #\"}'\n\nls -la /tmp/CCT_RCE_PROOF /tmp/CCT_AGENT_PROOF   # both created => injected commands ran\nThe aaaaaaaaaa padding satisfies the 10-char minimum, then ; (or $(...), or backticks) starts the injected command. claude/npx do not even need to be installed — the injected segment runs regardless.\n\nConfirmed at runtime on v1.28.13 (Node 22, Linux): both marker files were created, the server listened on *:3444, and an OPTIONS preflight from Origin: https://evil.example returned 200 with Access-Control-Allow-Origin: *.\n\nImpact\n\nUnauthenticated remote code execution (CWE-78) on any machine running --studio. Two reachability paths:\n- Drive-by: a developer running --studio who visits an attacker-controlled web page — the page's cross-origin fetch() (Content-Type application/json) passes the wildcard CORS preflight and delivers the POST, achieving RCE with no other interaction.\n- LAN: because the server binds 0.0.0.0, anyone on the same network (office, co-working space, public Wi-Fi) can hit port 3444 directly.\n\nImpact is full compromise of the developer's user account (arbitrary command execution with the developer's privileges): source code, SSH keys, cloud credentials, and .env secrets.\n\nSuggested fix\n\n- Remove shell: true from all three spawns so arguments stay discrete argv entries (kills the injection).\n- Validate agentName against a strict allowlist (^[A-Za-z0-9._/-]+$).\n- Bind to loopback only (app.listen(PORT, '127.0.0.1', ...)).\n- Replace the wildcard CORS with a same-origin allowlist and reject other origins.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "claude-code-templates"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.29.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.29.2"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/davila7/claude-code-templates/security/advisories/GHSA-79wm-x847-7cvg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-73222"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/davila7/claude-code-templates/commit/bc4618b07232633c1c0aac12a43e436268d31783"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/davila7/claude-code-templates"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/davila7/claude-code-templates/blob/main/CHANGELOG.md"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-306", "CWE-352", "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-03T19:50:47Z",
    "nvd_published_at" : "2026-08-11T19:18:51Z"
  }
}