Claude Code Templates: Unauthenticated OS command injection (RCE) in Claude Code Studio server (--studio)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-73222: 0.32% estimated exploitation activity in the next 30 days; percentile 24.97 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 childprocess.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…

Published by the source

3 Sep 2026, 19:50 UTC

Last modified by the source

3 Sep 2026, 19:50 UTC

Source last checked

26 Oct 2026, 13:02 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-79wm-x847-7cvg

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# Patch Next advisory brief: CVE-2026-73222

Advisory: Claude Code Templates: Unauthenticated OS command injection (RCE) in Claude Code Studio server (--studio)
IDs: CVE-2026-73222, GHSA-79wm-x847-7cvg
Record: https://patchnext.com/advisories/cve-2026-73222 (revision 1, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: claude-code-templates 1.29.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm claude-code-templates: affected <= 1.29.2; fixed in 1.29.4

## Suggested inspection (read-only)
- `npm ls claude-code-templates --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on claude-code-templates.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-79wm-x847-7cvg (GitHub-reviewed advisory GHSA-79wm-x847-7cvg lists affected ranges: npm claude-code-templates >=0 <=1.29.2)

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