Vulnerability details
CVE-2026-55580
mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist
Official 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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 8.6High | 4.0 | CVEProject cvelistV5 (CNA) (GitHub_M) | 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 |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| sonirico | mcp-shell | < 0.6.0 | CVEProject cvelistV5 (CNA) |
References and advisories
4- https://github.com/sonirico/mcp-shell/pull/16 x_refsource_MISC
- https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f x_refsource_MISC
- https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0 x_refsource_MISC
- https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m x_refsource_CONFIRM
Details
- Published
- 2026-08-25
- Last updated
- 2026-08-25
- State
- Published
- Assigner (CNA)
- GitHub_M
Exploit prediction (EPSS)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- Proof of concept
- Technical impact
- Total
Weaknesses (CWE)
- CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')