CVE-2026-55580: Sonirico Mcp-Shell

High severity, CVSS 8.6. EPSS: 0.2% chance of exploitation in the next 30 days.

mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, config.go initializes Security.Enabled to false, and when MCP_SHELL_SEC_CONFIG_FILE is unset, main.go starts the documented bare-binary deployment without a security policy. SecurityValidator.validateCommand in security.go then short-circuits and allows every command supplied to the shell_exec MCP tool, so an LLM connected over stdio can execute unrestricted OS commands as the mcp-shell process user. The README from-source installation and MCP client configuration omit MCP_SHELL_SEC_CONFIG_FILE, making the insecure state the documented default. This issue is fixed in version 0.6.0.

Affected products

• Sonirico Mcp-Shell: before 0.6.0 (fixed in 0.6.0)

Published 2026-08-25. Last modified 2026-09-09.