CVE-2026-55580

High

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.

SeverityHigh

CVSS8.6

Exploit probability—

ProductGithub.com/sonirico/mcp-shell

PublishedAug 25, 2026

First seenAug 25, 2026

Weakness typeCWE-78OS command injection

How to fix

Update

github.com/sonirico/mcp-shell0.6.0 or later

Affected products

Product	Affected versions	Fixed in
github.com/sonirico/mcp-shellGo	v < 0.6.0	0.6.0

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