CVE-2026-4496: Git-MCP-Server RCE Vulnerability

CVE-2026-4496 Overview

A command injection vulnerability has been identified in sigmade Git-MCP-Server affecting the child_process.exec function within the src/gitUtils.ts file. This vulnerability impacts the show_merge_diff, quick_merge_summary, and show_file_diff components, allowing attackers to inject and execute arbitrary operating system commands. The exploit has been publicly disclosed, and while the vendor was contacted regarding this issue, no response was received. Since Git-MCP-Server operates on a rolling release model, specific version identifiers are not available.

Critical Impact

Local attackers with low privileges can execute arbitrary OS commands through the vulnerable child_process.exec function, potentially leading to system compromise, data theft, or further lateral movement within the affected environment.

Affected Products

• Git-MCP-Server (up to commit 785aa159f262a02d5791a5d8a8e13c507ac42880)
• Affected component: src/gitUtils.ts
• Vulnerable functions: show_merge_diff, quick_merge_summary, show_file_diff

Discovery Timeline

• 2026-03-20 - CVE-2026-4496 published to NVD
• 2026-03-24 - Last updated in NVD database

Technical Details for CVE-2026-4496

Vulnerability Analysis

This vulnerability falls under CWE-77 (Improper Neutralization of Special Elements used in a Command), commonly known as OS Command Injection. The vulnerable code resides in the src/gitUtils.ts file where the child_process.exec function is used to execute Git operations. The affected functions—show_merge_diff, quick_merge_summary, and show_file_diff—fail to properly sanitize user-supplied input before passing it to the shell for execution. This allows a local attacker to inject malicious commands that will be executed with the privileges of the Node.js process running the Git-MCP-Server.

The attack requires local access to the system but only requires low privileges to execute. User interaction is not required for exploitation. The exploitation of this vulnerability could result in confidentiality, integrity, and availability impacts to the local system.

Root Cause

The root cause is the use of child_process.exec without proper input sanitization or validation. When constructing Git commands, user-controlled input such as file paths, branch names, or commit references are concatenated directly into command strings. This allows an attacker to break out of the intended command context by injecting shell metacharacters (such as ;, |, &&, or backticks) that cause additional commands to be executed.

The safer approach would be to use child_process.execFile or child_process.spawn with an array of arguments, which prevents shell interpretation of special characters.

Attack Vector

The attack must be initiated from a local position, meaning an attacker needs local access to the system running Git-MCP-Server. The attacker could craft malicious input through parameters passed to the vulnerable Git utility functions. For example, when invoking functions like show_file_diff with a crafted file path containing shell metacharacters, the injected commands would be executed by the underlying shell.

The vulnerability mechanism involves improper neutralization of special characters in user input before it is passed to child_process.exec. Technical details and a proof-of-concept are documented in the GitHub Issue #1 for Git-MCP-Server and the associated Bug Report PDF.

Detection Methods for CVE-2026-4496

Indicators of Compromise

• Unusual process spawning from Node.js processes running Git-MCP-Server
• Unexpected shell commands or subprocesses initiated by the application
• Suspicious Git-related operations with anomalous parameters containing shell metacharacters

Detection Strategies

• Monitor process execution chains for unexpected child processes spawned from Node.js or Git-MCP-Server
• Implement application-level logging to capture all parameters passed to Git utility functions
• Deploy file integrity monitoring on critical system files and directories

Monitoring Recommendations

• Enable verbose logging on systems running Git-MCP-Server to capture command execution details
• Set up alerts for process creation events where the parent process is the Git-MCP-Server application
• Review application logs for input containing shell metacharacters (;, |, &&, $(), backticks)

How to Mitigate CVE-2026-4496

Immediate Actions Required

• Apply the available patch from GitHub Pull Request #2
• Restrict local access to systems running Git-MCP-Server to trusted users only
• Implement network segmentation to limit the blast radius of potential exploitation
• Consider temporarily disabling the affected functions until the patch is applied

Patch Information

A patch addressing this vulnerability is available via GitHub Pull Request #2 for Git-MCP-Server. Since Git-MCP-Server operates on a rolling release basis with continuous delivery, users should pull the latest commits that include the security fix. The patch should replace the vulnerable child_process.exec calls with safer alternatives that do not interpret shell metacharacters. For additional context and technical details, refer to the VulDB entry #352045.

Workarounds

• Implement input validation at the application layer to reject parameters containing shell metacharacters
• Deploy application sandboxing or containerization to limit the impact of command execution
• Apply the principle of least privilege to the service account running Git-MCP-Server
• Use security modules (e.g., AppArmor, SELinux) to restrict what commands the application can execute

# Example: Restricting Git-MCP-Server process capabilities using AppArmor
# Create profile at /etc/apparmor.d/git-mcp-server
# Limit exec capabilities to only necessary Git binaries
/usr/bin/git ix,
deny /bin/** x,
deny /usr/bin/** x,