CVE-2026-55580
mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist
- State
- Published
- Severity
- 8.6 High
- Published
- Aug 25, 2026
- Updated
- Aug 25, 2026
- Reserved
- Jun 16, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.6 High | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N | GitHub_M |
Weaknesses
- CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Affected Products
| Product | Versions |
|---|---|
mcp-shellsonirico |
|
References
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