CVE-2026-55581
mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, the default Docker security.yaml includes /bin/bash in allowed_executables, while security.go validates only the first token and checkBlockedPatternsAndCommands does not reject the shell command-mode flag -c. A caller of the shell_exec MCP tool can provide the command argument `/bin/bash -c <arbitrary-command>`, which passes validation and reaches executor.go, where parseCommand and exec.CommandContext execute the arbitrary command as mcpuser outside the intended allowlist. This issue is fixed in version 0.6.0.
Scoring
- Severity
- HIGH
- CVSS base score
- 8.4
- CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS probability
- 0.34%
- CWE
- CWE-78, CWE-183, CWE-1188
- Published
- 2026-08-25
- Last modified
- 2026-08-25
Affected products
- sonirico mcp-shell
Weakness type
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