Vulnerability · Published Aug 25, 2026 · Assigned by GitHub_M
CVE-2026-55580mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist
High 8.6
In plain English
A high-severity OS command injection in mcp-shell from sonirico. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/sonirico/mcp-shell | 0.6.0 | GHSA-f5pj-2738-996m |
| Go | github.com/sonirico/mcp-shell | 0.6.0 | GO-2026-6292 |
Affected products (as reported)
Weakness: CWE-78 · Vector: 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
References
- https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m x_refsource_CONFIRM
- 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