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OpenAdvisories
High · 8.4 CVE-2026-55581 EUVD-2026-65549GHSA-3x77-wg38-92r3GO-2026-6290

mcp-shell: Secure Mode Allowlist Bypass via Default `/bin/bash` Executable

Published Aug 25, 2026 · Updated Aug 25, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
sonirico mcp-shell < 0.6.0 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
SLES for SAP 16.0 govulncheck-vulndb 0.0.20260827T195228-160000.1.1 SUSE-SU-2026:23625-1
SLES 16.0 govulncheck-vulndb 0.0.20260827T195228-160000.1.1 SUSE-SU-2026:23625-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 govulncheck-vulndb 0.0.20260827T195228-160000.1.1 openSUSE-SU-2026:21761-1

Affected packages

EcosystemPackageAffectedFixedRecord
Go github.com/sonirico/mcp-shell < 0.6.0 0.6.0 GHSA-3x77-wg38-92r3

Advisories 2

References