CVE-2026-55582 — mcp-shell is an MCP server for running shell commands securely, auditably, and on demand.¶

Key facts

CVE-2026-55582 is a High (8.4) vulnerability: mcp-shell is an MCP server for running shell commands securely, auditably, and on demand.. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-55582
Severity	High (8.4)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-55582/

Details¶

English | 한국어

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=!, 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.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-55582
Type	RCE
CVSS Score	8.4

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-55582/poc.py

Usage¶

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab¶

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start¶

# Clone and navigate to CVE directory
cd CVE-2026-55582

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints¶

Application	URL	Status
Vulnerable App	http://localhost:8080	Shows vulnerability
Patched App	http://localhost:8081	Demonstrates fix

Directory Structure¶

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References¶

https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f
https://github.com/sonirico/mcp-shell/pull/16
https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0
https://github.com/sonirico/mcp-shell/security/advisories/GHSA-74hp-mggr-hv58

Generated by PoC Generator on 2026-08-26T07:52:03.831884475

Frequently asked questions¶

What is CVE-2026-55582?¶

CVE-2026-55582 is a High (8.4) vulnerability: mcp-shell is an MCP server for running shell commands securely, auditably, and on demand.. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-55582?¶

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2026-55582?¶

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.