Compliance Impact

The vulnerability allows attackers to execute arbitrary commands on the Flowise host, potentially leading to unauthorized access, data breaches, and system compromise.

Such impacts on confidentiality, integrity, and availability can result in non-compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and secure system operations.

Specifically, exploitation could lead to exposure or manipulation of personal or health-related data, violating data protection requirements.

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Mitigation Strategies

The immediate and most effective mitigation is to upgrade Flowise to version 3.1.2 or later, where this vulnerability has been patched.

Until the upgrade can be applied, restrict access to the Flowise MCP server feature and API to trusted users only, especially limiting accounts with view/update permissions for chatflows.

Implement monitoring and alerting for suspicious command executions such as 'docker build' and 'npx --yes', and for node commands with file paths starting with '//'.

Consider applying network-level controls to limit exposure of the Flowise server and its API to untrusted networks.

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Executive Summary

CVE-2026-56274 is a critical security vulnerability in Flowise versions before 3.1.2 that allows attackers to execute arbitrary operating system commands on the host running Flowise.

The vulnerability arises from incomplete validation of command flags and a flaw in the regular expression used to restrict local file access in the Custom MCP Server feature. This allows attackers with any Flowise account or API access with view/update permissions to configure a malicious MCP server that bypasses security checks.

Specifically, certain commands like 'docker build' and 'npx --yes' are not properly blocked, and file paths starting with '//' bypass local file access restrictions, enabling remote code execution (RCE) on the server.

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Impact Analysis

This vulnerability can have severe impacts including full compromise of the Flowise host system.

• Attackers can execute arbitrary commands remotely, potentially gaining control over the host machine.
• If the attacker uses the 'docker build' command with a privileged container, they can achieve full control of the host.
• Execution of malicious npm packages via 'npx --yes' can lead to remote code execution.
• Bypassing local file access restrictions allows attackers to upload and execute malicious scripts.

Overall, the vulnerability threatens confidentiality, integrity, and availability of the affected system.

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Detection Guidance

Detection of this vulnerability involves monitoring for unusual or unauthorized use of commands that bypass the validateCommandFlags blocklist, such as 'docker build' or 'npx --yes', especially when configured via the MCP server feature.

You can check for suspicious MCP server configurations or API calls that attempt to use these commands. Additionally, monitoring for execution of node commands with file paths starting with '//' could indicate attempts to bypass local file access restrictions.

Specific commands to detect exploitation attempts might include:

• Review Flowise logs or API access logs for commands containing 'docker build' or 'npx --yes'.
• Use system process monitoring tools (e.g., 'ps aux | grep docker' or 'ps aux | grep npx') to identify unexpected command executions.
• Search for node command executions with suspicious file paths, e.g., 'ps aux | grep node' and check for arguments starting with '//'.
• Monitor network traffic for unusual MCP server communications or API requests that configure MCP servers.

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