CVE-2026-81097
Received Received - Intake

Command Injection in execute_ruby Sandbox

Publication date: 2026-08-27

Last updated on: 2026-08-27

Assigner: VulnCheck

Description
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 Scores

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Meta Information

Published
2026-08-27
Last Modified
2026-08-27
Generated
2026-08-27
AI Q&A
2026-08-27
EPSS Evaluated
N/A
NVD
CVE-2026-81097
EUVD
EUVD-2026-67025

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
maquina-app rails-mcp-server to 1.6.0 (inc)
maquina-app rails-mcp-server 1.6.1
maquina-app rails-mcp-server 2.0.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-78 The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Attack-Flow Graph

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Executive Summary

The execute_ruby tool is meant to be a read-only Ruby sandbox but has a flaw. It uses a denylist to block dangerous methods but misses some process-spawning entry points in the pseudo-terminal library. This allows normal tool calls to bypass restrictions and start a shell, executing commands as the server account outside the sandbox.

Impact Analysis

An attacker could exploit this to run arbitrary commands on the server running the sandbox. This could lead to data theft, system compromise, or unauthorized access to sensitive information. The high CVSS scores indicate significant impact on confidentiality, integrity, and availability.

Compliance Impact

This vulnerability could lead to unauthorized data access or exfiltration, violating GDPR's data protection principles or HIPAA's security requirements for protected health information. Compliance may be compromised if the system handles regulated data.

Mitigation Strategies

Upgrade the execute_ruby tool to version 1.6.1 or later to address the denylist gap and restrict requires to a data-only list. Consider upgrading to version 2.0.0 which removes the tool entirely.

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