CVE-2026-2131: HarmonyOS-mcp-server RCE Vulnerability

CVE-2026-2131 Overview

A critical OS command injection vulnerability has been identified in XixianLiang HarmonyOS-mcp-server version 0.1.0. This vulnerability affects the input_text function, where improper handling of the text argument allows attackers to inject and execute arbitrary operating system commands. The vulnerability can be exploited remotely, and a public exploit is reportedly available.

Critical Impact

Remote attackers can leverage this command injection vulnerability to execute arbitrary OS commands on the target system, potentially leading to complete system compromise, data theft, or lateral movement within the network.

Affected Products

• XixianLiang HarmonyOS-mcp-server version 0.1.0

Discovery Timeline

• 2026-02-08 - CVE-2026-2131 published to NVD
• 2026-02-09 - Last updated in NVD database

Technical Details for CVE-2026-2131

Vulnerability Analysis

This vulnerability is classified as CWE-77: Improper Neutralization of Special Elements used in a Command (Command Injection). The input_text function in HarmonyOS-mcp-server fails to properly sanitize or validate user-supplied input through the text parameter before passing it to system shell commands.

When user input containing shell metacharacters or command separators (such as ;, |, &&, or backticks) is processed by the vulnerable function, the underlying system interprets these as command delimiters, allowing attackers to append or inject additional commands that execute with the privileges of the application process.

The MCP (Model Context Protocol) server architecture makes this particularly dangerous, as these servers are designed to handle automated inputs that may originate from various sources, including potentially untrusted AI model outputs or external integrations.

Root Cause

The root cause stems from insufficient input validation and sanitization in the input_text function. The application directly incorporates user-controlled data into shell command execution without proper escaping or use of parameterized command execution methods. This is a common vulnerability pattern when developers concatenate user input directly into command strings rather than using safe APIs that separate command structure from data.

Attack Vector

The attack vector is network-based, requiring no user interaction. An authenticated attacker with low privileges can craft malicious input containing OS command sequences and submit it through the text parameter of the input_text function. The injected commands execute in the context of the HarmonyOS-mcp-server process, potentially allowing:

• Arbitrary file read/write operations
• Reverse shell establishment
• System reconnaissance and enumeration
• Pivot attacks to other networked systems
• Data exfiltration
• Service disruption

The vulnerability mechanism involves improper handling of shell metacharacters in user input. When the input_text function processes the text argument, it fails to sanitize special characters that have meaning to the operating system shell. An attacker can craft input containing command separators or subshell execution syntax to inject arbitrary commands. For detailed technical analysis, refer to the GitHub RCE Vulnerability Report.

Detection Methods for CVE-2026-2131

Indicators of Compromise

• Unusual process spawning from the HarmonyOS-mcp-server process, particularly shell processes (/bin/sh, /bin/bash, cmd.exe)
• Network connections initiated by the MCP server to unexpected external destinations
• Unexpected file system modifications or access patterns in server directories
• Log entries containing shell metacharacters (;, |, &&, $(), backticks) in text input fields

Detection Strategies

• Implement application-level logging to capture all input processed by the input_text function
• Deploy web application firewalls (WAF) or input validation proxies to detect command injection patterns
• Monitor process execution trees for child processes spawned by the MCP server application
• Utilize SentinelOne's behavioral AI to detect anomalous process execution patterns indicative of command injection exploitation

Monitoring Recommendations

• Enable verbose logging for all MCP server API endpoints
• Configure SIEM rules to alert on shell metacharacter patterns in application logs
• Monitor system call activity for the MCP server process to detect unexpected exec() or system() calls
• Review network traffic from the server for signs of reverse shell connections or data exfiltration

How to Mitigate CVE-2026-2131

Immediate Actions Required

• Restrict network access to HarmonyOS-mcp-server to trusted sources only
• Implement network segmentation to isolate the MCP server from critical systems
• Deploy additional input validation at the network perimeter using WAF rules for command injection patterns
• Consider disabling the vulnerable input_text functionality until a patch is available

Patch Information

At the time of publication, no official patch has been released for this vulnerability. Organizations should monitor the VulDB entry and vendor communications for patch availability. When a fix becomes available, prioritize testing and deployment based on your organization's risk assessment.

Workarounds

• Implement strict input validation to reject or escape shell metacharacters in the text parameter
• Use allowlist-based input validation permitting only expected character sets
• Run the HarmonyOS-mcp-server with minimal system privileges to limit the impact of successful exploitation
• Deploy application-layer firewall rules to filter requests containing command injection patterns

# Example: Restrict network access to HarmonyOS-mcp-server using iptables
# Allow only trusted IP ranges to access the MCP server port
iptables -A INPUT -p tcp --dport 8080 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP