CVE-2026-73601: Flowise before 3.1.3 Remote Code Execution via Custom MCP

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-13 · updated 2026-10-24
Weakness: CWE-95

Description

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.

Affected products

FlowiseAI Flowise: before 3.1.3 — fixed in 3.1.3

How to fix

Upgrade to a fixed version: FlowiseAI Flowise 3.1.3. Check the vendor advisory for mitigations.

References

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