CVE-2026-55580

Description

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.

References

• https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f
• https://github.com/sonirico/mcp-shell/pull/16
• https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0
• https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m
• https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m