CVE-2025-53818: GitHub Kanban MCP Server RCE Vulnerability

CVE-2025-53818 Overview

CVE-2025-53818 is a command injection vulnerability in the GitHub Kanban MCP Server, a Model Context Protocol (MCP) server designed for managing GitHub issues in Kanban board format and streamlining LLM task management. Version 0.3.0 of the MCP Server contains an unsafe implementation in its tool definition that allows attackers to inject arbitrary commands through the add_comment functionality.

Critical Impact

Remote attackers can execute arbitrary commands on the server by exploiting the vulnerable add_comment tool, which uses Node.js child_process.exec() API with unsanitized user input to execute GitHub CLI commands.

Affected Products

• GitHub Kanban MCP Server version 0.3.0
• MCP Server implementations using add_comment tool with child_process.exec()
• Systems running vulnerable versions of Sunwood-ai-labs/github-kanban-mcp-server

Discovery Timeline

• 2025-07-14 - CVE-2025-53818 published to NVD
• 2025-07-15 - Last updated in NVD database

Technical Details for CVE-2025-53818

Vulnerability Analysis

This command injection vulnerability (CWE-78) exists in the add_comment tool implementation within the GitHub Kanban MCP Server. The vulnerability stems from the server's use of Node.js child_process.exec() API to execute GitHub CLI (gh) commands. When user-supplied input is concatenated directly into the command string without proper sanitization or validation, attackers can inject malicious shell commands that will be executed with the privileges of the server process.

The vulnerable code pattern is located in the comment handlers at src/handlers/comment-handlers.ts and the tool handlers at src/handlers/tool-handlers.ts. The exec() function spawns a shell to run the command, making it particularly dangerous when combined with unsanitized input, as shell metacharacters can be used to chain additional commands.

Root Cause

The root cause is the use of the unsafe child_process.exec() API combined with string concatenation of untrusted user input. The exec() function in Node.js spawns a shell and is inherently vulnerable to command injection when user input is not properly sanitized. Secure alternatives such as execFile() or spawn() with argument arrays should be used instead, as they do not invoke a shell interpreter and are not susceptible to shell metacharacter injection.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by providing specially crafted input to the add_comment MCP tool. By including shell metacharacters such as semicolons, backticks, or command substitution syntax in the comment content, the attacker can break out of the intended gh command and execute arbitrary commands on the underlying system.

For example, an attacker could craft a comment containing shell escape sequences that, when passed to exec(), would execute additional commands beyond the intended GitHub CLI operation. This could lead to complete server compromise, data exfiltration, or lateral movement within the infrastructure.

Technical details regarding the vulnerable implementation can be found in the GitHub Security Advisory GHSA-6jx8-rcjx-vmwf and the source code comment handler.

Detection Methods for CVE-2025-53818

Indicators of Compromise

• Unexpected processes spawned as children of the Node.js MCP server process
• Unusual command-line arguments containing shell metacharacters (;, |, $(), backticks) in server logs
• Network connections to unexpected external hosts originating from the server process
• Modification of system files or creation of new files outside expected directories
• Presence of reverse shell connections or unexpected listening ports

Detection Strategies

• Monitor process execution chains for suspicious child processes spawned by Node.js applications
• Implement application-level logging to capture all inputs to the add_comment tool and flag those containing shell metacharacters
• Deploy file integrity monitoring on critical system directories to detect unauthorized modifications
• Use network monitoring to identify unusual outbound connections from the MCP server

Monitoring Recommendations

• Enable comprehensive logging for all MCP tool invocations and their parameters
• Configure SIEM rules to alert on command injection patterns in application logs
• Monitor for anomalous process behavior using endpoint detection and response (EDR) solutions
• Implement runtime application self-protection (RASP) to detect and block command injection attempts

How to Mitigate CVE-2025-53818

Immediate Actions Required

• Disable or restrict access to the add_comment tool until a patch is available
• Implement network segmentation to limit the blast radius if exploitation occurs
• Apply strict input validation at the application boundary to reject inputs containing shell metacharacters
• Review and audit all MCP tool implementations for similar unsafe patterns
• Consider running the MCP server in a sandboxed environment with minimal privileges

Patch Information

As of the publication date, no official patch is available for this vulnerability. The vendor has acknowledged the issue in GitHub Security Advisory GHSA-6jx8-rcjx-vmwf. Organizations should monitor the repository for updates and apply patches as soon as they become available. The v0.4.0 comment handler may contain relevant updates.

Workarounds

• Replace child_process.exec() calls with execFile() or spawn() using argument arrays to prevent shell interpretation
• Implement strict input validation using allowlists for permitted characters in comment content
• Deploy a web application firewall (WAF) or API gateway with command injection detection rules
• Run the MCP server in a containerized environment with restricted capabilities and read-only filesystems where possible

# Example: Restrict MCP server process capabilities
# Run the server with minimal permissions
docker run --read-only --cap-drop=ALL --security-opt=no-new-privileges \
  --network=internal github-kanban-mcp-server:latest