What’s Vulnerable › Vulnerabilities

CVE-2026-55580: mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist

• Severity: high (CVSS 8.6 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-25 · updated 2026-09-09
• Weakness: CWE-78

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.

Affected products

• sonirico mcp-shell: before 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

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