CVEvulnerability

CVE-2026-55581

8.4 HIGH Published 2026-08-25 Modified 2026-09-09 Official page ↗
Status
Deferred
Published
2026-08-25
Last modified
2026-09-09
Assigner
[email protected]
CVSS 3.1 ([email protected])
8.4 HIGH — CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses
CWE-1188, CWE-183, CWE-78

Description

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.

Related

Weakness · CWE (3)

  • CWE-1188 Initialization of a Resource with an Insecure Default weakness
  • CWE-183 Permissive List of Allowed Inputs weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command weakness

References