CVE-2026-5802: mcp-javadc RCE Vulnerability

CVE-2026-5802 Overview

A command injection vulnerability has been identified in idachev mcp-javadc versions up to 1.2.4. The vulnerability exists in the HTTP Interface component, where the jarFilePath argument is improperly handled, allowing attackers to inject arbitrary operating system commands. This flaw can be exploited remotely without authentication, making it a significant security concern for any deployments exposing the HTTP interface.

Critical Impact

Remote attackers can execute arbitrary OS commands on the target system through the HTTP Interface by manipulating the jarFilePath parameter, potentially leading to complete system compromise.

Affected Products

• idachev mcp-javadc up to version 1.2.4

Discovery Timeline

• April 8, 2026 - CVE-2026-5802 published to NVD
• April 8, 2026 - Last updated in NVD database

Technical Details for CVE-2026-5802

Vulnerability Analysis

This vulnerability is classified as CWE-77 (Improper Neutralization of Special Elements used in a Command), commonly known as OS Command Injection. The flaw resides in the HTTP Interface component of the mcp-javadc application, which fails to properly sanitize user-controlled input in the jarFilePath argument before passing it to system shell commands.

When the application processes requests containing the jarFilePath parameter, it constructs system commands using the provided value without adequate input validation or sanitization. This allows attackers to append or inject malicious shell commands by embedding special characters such as semicolons, pipes, or backticks within the parameter value.

The vulnerability can be exploited remotely over the network without requiring any authentication or user interaction, making it particularly dangerous in exposed deployments. While the immediate impact is categorized as limited confidentiality, integrity, and availability compromise, successful exploitation could serve as an initial foothold for further attacks.

Root Cause

The root cause of this vulnerability is insufficient input validation and sanitization of the jarFilePath parameter within the HTTP Interface component. The application fails to implement proper escaping or allowlist-based validation before incorporating user-supplied data into shell commands, allowing special characters to be interpreted as command separators or operators by the underlying operating system shell.

Attack Vector

The attack vector is network-based, allowing remote exploitation through the HTTP Interface. An attacker can craft malicious HTTP requests containing OS command injection payloads in the jarFilePath parameter. The exploit is publicly available according to the vulnerability disclosure, and the project maintainers have been notified through an issue report but have not yet responded.

The attack requires no authentication and no user interaction. Attackers can potentially:

• Execute arbitrary system commands with the privileges of the application
• Read sensitive files from the server
• Establish reverse shells for persistent access
• Pivot to other systems on the internal network

For technical details on the exploitation mechanism, refer to the GitHub Issue Discussion and VulDB Vulnerability Details.

Detection Methods for CVE-2026-5802

Indicators of Compromise

• Unusual HTTP requests to the mcp-javadc HTTP Interface containing special characters (;, |, &, backticks, $()) in the jarFilePath parameter
• Unexpected process spawning from the mcp-javadc application process
• Outbound network connections initiated by the application server to unknown destinations
• Presence of suspicious files or scripts in application directories

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block command injection patterns in HTTP parameters
• Monitor application logs for requests containing shell metacharacters in the jarFilePath parameter
• Deploy endpoint detection and response (EDR) solutions to identify suspicious command execution chains
• Use SentinelOne's behavioral AI to detect anomalous process execution from the Java application

Monitoring Recommendations

• Enable verbose logging on the mcp-javadc HTTP Interface to capture all incoming requests
• Set up alerts for process creation events originating from the Java application context
• Monitor network traffic for unusual outbound connections from servers running mcp-javadc
• Implement file integrity monitoring on critical system directories

How to Mitigate CVE-2026-5802

Immediate Actions Required

• Restrict network access to the mcp-javadc HTTP Interface to trusted IP addresses only
• Place the application behind a reverse proxy with input validation capabilities
• Consider disabling the HTTP Interface if not strictly required for operations
• Audit existing logs for signs of exploitation attempts

Patch Information

As of the last update on April 8, 2026, the project maintainers have been notified of the vulnerability through an issue report but have not yet responded. No official patch is currently available. Organizations should monitor the GitHub Project Repository for updates and apply patches as soon as they become available.

Workarounds

• Implement a web application firewall (WAF) with rules to block command injection patterns targeting the jarFilePath parameter
• Use network segmentation to isolate systems running mcp-javadc from critical infrastructure
• Deploy input validation at the network perimeter using an API gateway or reverse proxy
• Consider replacing mcp-javadc with an alternative solution until an official patch is released

# Example: Restrict access to mcp-javadc HTTP interface using iptables
# Allow only trusted IP addresses to access the service port
iptables -A INPUT -p tcp --dport <HTTP_PORT> -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport <HTTP_PORT> -j DROP