Flowise: Flowise versions before 3.1.3 contain a remote code execution vulnerability in the Custom MCP…
Flowise
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- Severity
- High, CVSS 8.8
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Record
- CVE-2026-73601
- Affects
- Flowise
- Known exploited
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- August 13, 2026
- Source last modified
- October 24, 2026
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.
Description quoted from the NVD record.
Who is affected
Flowise is a tool for building apps and workflows that use AI language models. This flaw affects Flowise versions before 3.1.3. The problem is in the Custom MCP building block, which lets a workflow connect to outside tools. It only applies when that building block is set up to start those tools as programs on the same computer (the "stdio" setting). In that setup, anyone with a login to Flowise could get around the product's safety checks and run any commands they like on the computer that runs it. This flaw is rated High.
What to do
- Find out who looks after Flowise in your organization: the person who installed it or runs it, or an IT provider or vendor that manages it for you.
- If your own staff or volunteers run it, ask that person to check which version is installed. Versions before
3.1.3have this flaw. - That person should update Flowise to version
3.1.3or later. The vendor advisory linked on this page has more details. - If an IT provider or vendor runs Flowise for you, send them this advisory and ask when the update will be done.
Analysis written from the source record as of October 24, 2026 and reviewed before publishing.