FlowiseAI Flowise up to 3.1.2 Custom MCP node PYTHONWARNINGS/BROWSER os command injection

Summaryinfo

A vulnerability was found in FlowiseAI Flowise up to 3.1.2. It has been declared as critical. The impacted element is an unknown function of the component Custom MCP node. Executing a manipulation of the argument PYTHONWARNINGS/BROWSER can lead to os command injection. The identification of this vulnerability is CVE-2026-73601. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in FlowiseAI Flowise up to 3.1.2. It has been declared as critical. This vulnerability affects some unknown processing of the component Custom MCP node. The manipulation of the argument PYTHONWARNINGS/BROWSER with an unknown input leads to a os command injection vulnerability. The CWE definition for the vulnerability is CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Flowise versions before 3.1.3 contain a remote code execution vulnerability in the Custom MCP node when CUSTOM_MCP_PROTOCOL is set to stdio, allowing authenticated users to execute arbitrary commands by manipulating environment variables and command arguments. Attackers can abuse PYTHONWARNINGS and BROWSER environment variables with python3, or leverage the root working directory with node to bypass validation and execute system commands.

The advisory is available at github.com. This vulnerability was named CVE-2026-73601 since 08/13/2026. The exploitation appears to be easy. The attack can be initiated remotely. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1202 by the MITRE ATT&CK project.

Upgrading to version 3.1.3 eliminates this vulnerability.

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Productinfo

Vendor

• FlowiseAI

Name

• Flowise

Version

• 3.1.0
• 3.1.1
• 3.1.2

Website

• Product: https://github.com/FlowiseAI/Flowise/

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