Executive Summary

CVE-2026-5831 is a command injection vulnerability in the Agions taskflow-ai project, affecting versions up to 2.1.8. The flaw exists in the MCP CallTool handler, specifically in the hidden tool named `terminal_execute`. This tool accepts a command string where only the first token is validated against an allowlist, while the rest of the command is passed unsanitized to Node.js's execSync function.

Because of this improper validation, an attacker can inject shell metacharacters and arbitrary OS commands remotely, leading to execution of unintended commands on the host system.

The vulnerability arises from the request handler forwarding arbitrary tool names without verifying if they are registered or exposed, and the executor not properly sanitizing the entire command string before execution.

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Compliance Impact

The vulnerability allows remote OS command injection, which can lead to full host compromise including data exposure, unauthorized alteration of server state, and service disruption.

Such impacts on confidentiality, integrity, and availability of data and services can negatively affect compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and system integrity.

However, the provided information does not explicitly mention compliance implications or specific regulatory impacts.

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Impact Analysis

This vulnerability can have severe impacts including:

• Confidentiality: High risk of exposure of sensitive host or system data.
• Integrity: High risk of unauthorized modification of server state or data.
• Availability: High risk of service disruption due to malicious command execution.

Since the vulnerability allows remote attackers to execute arbitrary OS commands with the permissions of the running process, it can lead to full host compromise.

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Detection Guidance

Detection of this vulnerability involves identifying attempts to invoke the hidden tool `terminal_execute` or other unregistered tools via the MCP CallTool handler, which is not listed in the advertised tools. Monitoring for unusual or unauthorized CallTool requests that include command strings with shell metacharacters (e.g., `;`, `&`, `|`) can indicate exploitation attempts.

Since the vulnerability allows OS command injection through unsanitized command strings passed to Node.js's execSync, commands that attempt to execute shell metacharacters or arbitrary commands remotely are suspicious.

• Monitor network traffic or logs for requests targeting the MCP CallTool handler with tool names like `terminal_execute`.
• Look for command strings containing shell metacharacters such as `;`, `&`, `|`, `$`, `(`, `)`, `{`, `}`, `[`, `]`, `<`, `>`, `!`, `*`, `?`.
• Use logging or intrusion detection systems to flag execution of commands that include suspicious patterns like `echo executor_poc; id` or similar injected commands.

Specific commands to detect exploitation attempts are not provided in the resources, but general approaches include inspecting server logs for unexpected CallTool invocations and using network monitoring tools to detect suspicious payloads.

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Mitigation Strategies

The primary immediate mitigation step is to upgrade the affected component to version 2.1.9 or later, which contains the security patch that fixes this vulnerability.

• Upgrade taskflow-ai to version 2.1.9 using the command: `npm install taskflow-ai@latest`.

The patch includes validation of tool names against a predefined registry to prevent execution of hidden or unregistered tools, blocking of shell metacharacters in terminal commands, and disabling shell interpretation in execSync calls.

• Ensure that the system rejects CallTool requests for tool names not registered or exposed.
• Implement authentication, authorization, logging, and rate limiting on sensitive MCP handlers to reduce risk.

If immediate upgrade is not possible, consider restricting access to the MCP CallTool handler and monitoring for suspicious activity as a temporary workaround.

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