Rails Mcp Server
Monthly
OS command injection in maquina-app rails-mcp-server versions 1.4.0 through 1.6.0 allows any caller with access to the execute_ruby MCP tool to escape the purported Ruby sandbox and execute arbitrary shell commands as the server process owner. The execute_ruby tool's denylist blocked Kernel#system, exec, and backtick invocations but never covered Ruby's pseudo-terminal library (PTY) entry points - PTY.spawn and PTY.getpty - enabling a caller to require 'pty' and spawn a child process entirely outside the guarded method replacements. No public exploit has been identified at time of analysis, and the vulnerability is not listed in CISA KEV, but the bypass path is fully documented in the vendor's public patch PR.
OS command injection in maquina-app rails-mcp-server versions 1.4.0 through 1.6.0 allows any caller with access to the execute_ruby MCP tool to escape the purported Ruby sandbox and execute arbitrary shell commands as the server process owner. The execute_ruby tool's denylist blocked Kernel#system, exec, and backtick invocations but never covered Ruby's pseudo-terminal library (PTY) entry points - PTY.spawn and PTY.getpty - enabling a caller to require 'pty' and spawn a child process entirely outside the guarded method replacements. No public exploit has been identified at time of analysis, and the vulnerability is not listed in CISA KEV, but the bypass path is fully documented in the vendor's public patch PR.