CVE-2026-5833: mcp-server-taskwarrior RCE Vulnerability

CVE-2026-5833 Overview

A command injection vulnerability has been identified in awwaiid mcp-server-taskwarrior versions up to 1.0.1. This security flaw impacts the function server.setRequestHandler within the file index.ts. Through manipulation of the Identifier argument, attackers can inject arbitrary commands that execute in the context of the application. The attack requires local access to be carried out successfully.

The vulnerability has been publicly disclosed, and an exploit is available. The vendor responded professionally and promptly released a patched version. The specific fix is identified by commit hash 1ee3d282debfa0a99afeb41d22c4b2fd5a3148f2.

Critical Impact

Local attackers with access to the system can inject malicious commands through the Identifier parameter, potentially leading to arbitrary command execution, data manipulation, or further system compromise.

Affected Products

• mcp-server-taskwarrior up to version 1.0.1
• Applications using the vulnerable server.setRequestHandler function in index.ts
• Systems running unpatched versions of the MCP Server Taskwarrior integration

Discovery Timeline

• 2026-04-09 - CVE-2026-5833 published to NVD
• 2026-04-09 - Last updated in NVD database

Technical Details for CVE-2026-5833

Vulnerability Analysis

This vulnerability is classified as CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), commonly known as injection. The flaw exists in the request handler logic within index.ts, where user-supplied input via the Identifier argument is processed without proper sanitization before being passed to command execution functions.

The MCP (Model Context Protocol) server for Taskwarrior is designed to provide integration between AI assistants and the Taskwarrior task management system. When processing requests through server.setRequestHandler, the application fails to properly validate or escape the Identifier parameter, allowing specially crafted input to break out of the intended command context and execute arbitrary system commands.

Root Cause

The root cause of this vulnerability stems from the use of execSync from Node.js's child_process module, which passes arguments through a shell interpreter. When untrusted input is included in the command string, an attacker can inject shell metacharacters to execute additional commands. The fix replaces execSync with execFileSync, which directly invokes the specified executable without shell interpolation, effectively preventing command injection attacks.

Attack Vector

This is a local attack vector vulnerability. An attacker with local access to the system running mcp-server-taskwarrior can craft malicious input containing shell metacharacters (such as ;, |, &&, or backticks) within the Identifier parameter. When this input is processed by server.setRequestHandler, the injected commands execute with the privileges of the application process.

The following code shows the security patch that addresses this vulnerability:

 import { diffLines, createTwoFilesPatch } from 'diff';
 import { minimatch } from 'minimatch';
 
-import { execSync } from 'child_process';
+import { execFileSync } from 'child_process';
 
 // Schema definitions
 

Source: GitHub Commit Details

This patch replaces execSync with execFileSync, which executes commands directly without invoking a shell, thereby eliminating the shell injection attack surface.

Detection Methods for CVE-2026-5833

Indicators of Compromise

• Unusual command execution patterns originating from the mcp-server-taskwarrior process
• Log entries showing malformed or suspicious Identifier parameters containing shell metacharacters (;, |, &&, $(), backticks)
• Unexpected child processes spawned by the Node.js application running the MCP server
• File system modifications or network connections initiated by the taskwarrior integration that deviate from normal behavior

Detection Strategies

• Monitor process execution chains for unexpected commands spawned by the mcp-server-taskwarrior application
• Implement application-level logging to capture all Identifier parameter values passed to server.setRequestHandler
• Deploy endpoint detection rules to identify command injection patterns in arguments passed to Node.js processes
• Review application logs for failed command executions that may indicate exploitation attempts

Monitoring Recommendations

• Enable verbose logging for the mcp-server-taskwarrior application to capture all incoming requests and parameter values
• Configure SentinelOne to monitor for suspicious command-line patterns indicating shell injection attempts
• Establish baseline behavior for the MCP server process and alert on deviations such as unexpected network connections or file access
• Implement file integrity monitoring on critical system directories to detect post-exploitation activities

How to Mitigate CVE-2026-5833

Immediate Actions Required

• Update mcp-server-taskwarrior to a version containing commit 1ee3d282debfa0a99afeb41d22c4b2fd5a3148f2 or later
• If immediate patching is not possible, restrict local access to systems running the vulnerable application
• Review logs for any evidence of exploitation attempts against the vulnerable Identifier parameter
• Audit any systems that may have been compromised and perform incident response procedures if exploitation is confirmed

Patch Information

The vendor has released a security patch addressing this command injection vulnerability. The fix is available in commit 1ee3d282debfa0a99afeb41d22c4b2fd5a3148f2. The patch modifies index.ts to use execFileSync instead of execSync, preventing shell interpretation of user-supplied input.

Additional details about this vulnerability can be found in GitHub Issue #8 and the VulDB entry #356289.

Workarounds

• Restrict local system access to trusted users only until the patch can be applied
• Implement input validation at the application layer to reject Identifier values containing shell metacharacters
• Run the mcp-server-taskwarrior process with minimal system privileges to limit the impact of successful exploitation
• Consider disabling the vulnerable functionality temporarily if it is not business-critical

# Update mcp-server-taskwarrior to the latest patched version
npm update mcp-server-taskwarrior

# Alternatively, install directly from the patched commit
npm install github:awwaiid/mcp-server-taskwarrior#1ee3d282debfa0a99afeb41d22c4b2fd5a3148f2