CVE-2026-55581

Summary

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.

Affected Software

VendorProductVersion RangeStatus
soniricomcp-shell< 0.6.0affected

Weaknesses

  • CWE-78: CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
  • CWE-183: CWE-183: Permissive List of Allowed Inputs
  • CWE-1188: CWE-1188: Insecure Default Initialization of Resource

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: no
    • Technical Impact: total

Additional References

References