mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, the default security.yaml allows /usr/bin/git, while security.go omits ! from containsShellMetacharacters and containsDangerousShellConstructs and applies no per-executable argument policy. A caller of the shell_exec MCP tool can provide the command argument /usr/bin/git -c alias.pwn=!<arbitrary-command>, causing Git to create a shell alias and execute arbitrary OS commands as the mcp-shell process user. The default Docker image runs as mcpuser with Git installed and secure mode enabled, so the bypass is exploitable in the default deployment without additional authentication beyond MCP connectivity. This issue is fixed in version 0.6.0.
History

Tue, 25 Aug 2026 18:00:00 +0000

Type Values Removed Values Added
First Time appeared Sonirico
Sonirico mcp-shell
Vendors & Products Sonirico
Sonirico mcp-shell

Tue, 25 Aug 2026 16:00:00 +0000

Type Values Removed Values Added
Description mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, the default security.yaml allows /usr/bin/git, while security.go omits ! from containsShellMetacharacters and containsDangerousShellConstructs and applies no per-executable argument policy. A caller of the shell_exec MCP tool can provide the command argument /usr/bin/git -c alias.pwn=!<arbitrary-command>, causing Git to create a shell alias and execute arbitrary OS commands as the mcp-shell process user. The default Docker image runs as mcpuser with Git installed and secure mode enabled, so the bypass is exploitable in the default deployment without additional authentication beyond MCP connectivity. This issue is fixed in version 0.6.0.
Title mcp-shell: Secure Mode Allowlist Bypass via Git Shell Alias
Weaknesses CWE-78
References
Metrics cvssV3_1

{'score': 8.4, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-25T15:37:43.486Z

Reserved: 2026-06-16T23:18:03.169Z

Link: CVE-2026-55582

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-25T16:16:55.650

Modified: 2026-08-25T16:16:55.650

Link: CVE-2026-55582

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-25T19:00:08Z