CVE-2026-81097

HIGH 8.4

rails-mcp-server 1.4.0 through 1.6.0 OS Command Execution via execute_ruby PTY Escape

CVSS Score

8.4

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-78
Vendor	maquina-app
Product	rails-mcp-server
Published	Aug 27, 2026

Stay Ahead of the Next One

Get instant alerts for maquina-app rails-mcp-server

Be the first to know when new high vulnerabilities affecting maquina-app rails-mcp-server are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

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

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

maquina-app / rails-mcp-server

1.4.0 ≤ 1.6.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/maquina-app/rails-mcp-server github.com: https://github.com/maquina-app/rails-mcp-server/pull/59 github.com: https://github.com/maquina-app/rails-mcp-server/releases vulncheck.com: https://www.vulncheck.com/advisories/rails-mcp-server-1.4.0-through-1.6.0-os-command-execution-via-execute-ruby-pty-escape

Credits

Avishai Gonen (Pluto Security)