CVE-2026-55581 (GCVE-0-2026-55581)

Vulnerability from cvelistv5 – Published: 2026-08-25 15:40 – Updated: 2026-08-25 19:01
VLAI
Title
mcp-shell: Secure Mode Allowlist Bypass via Default `/bin/bash` Executable
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.
SSVC
Exploitation: poc Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-25 19:01 UTC
CWE
  • CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
  • CWE-183 - Permissive List of Allowed Inputs
  • CWE-1188 - Insecure Default Initialization of Resource
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7661 records in the last 180 days details
Impacted products
Vendor Product Version CPE status
sonirico mcp-shell Affected: < 0.6.0
guessed Create a notification for this product.
Show details on NVD website

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