CVE-2026-81097rails-mcp-server 1.4.0 through 1.6.0 OS Command Execution via execute_ruby PTY Escape
Updated under an hour ago ()
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It affects maquina-app rails-mcp-server. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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The execute_ruby tool is documented as a read-only Ruby sandbox and is enforced by a pattern denylist together with replacements for the process-spawning methods on Kernel. The pseudo-terminal library's spawn entry points are neither in the denylist nor replaced, so a normal tool call could reach them and start a shell, executing commands as the account running the server and outside the guarded methods. The denylist was introduced with the tool in 1.4.0 and never covered those entry points through 1.6.0. Version 1.6.1 restricts the requires the sandbox permits to a data-only list and blocks dynamic dispatch to execution entry points; 2.0.0 removes the tool.
- CVSS
- 8.4 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-78
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Deferred
- Record last updated
- Aug 29, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
maquina-app rails-mcp-server maquina_app:rails_mcp_server (from the name) | from 1.4.0 through 1.6.0 | CNA record |
References
- https://github.com/maquina-app/rails-mcp-serverproduct
- https://github.com/maquina-app/rails-mcp-server/pull/59issue-tracking, patch
- https://github.com/maquina-app/rails-mcp-server/releasesrelease-notes
- https://www.vulncheck.com/advisories/rails-mcp-server-1.4.0-through-1.6.0-os-command-execution-via-execute-ruby-pty-escapethird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.