CVE-2026-40933: Flowise command execution through Custom MCP stdio server configuration

Summary

Flowise versions prior to 3.1.0 contain a flaw in the MCP adapter's serialization of stdio commands. An authenticated user can add an MCP stdio server through the "Custom MCP" configuration with an arbitrary command, bypassing validateCommandInjection and validateArgsForLocalFileAccess by pairing an allowed command such as "npx" with code execution arguments like "-c touch /tmp/pwn", which achieves command execution on the underlying OS.

Mitigation

Fixed in 3.1.0.

Affected packages in the Exposure Registry

Matched by package name and ecosystem. Each entry shows whether the package delegates to a language model and how many tracked packages depend on it.

• flowisenpmLLM dependency since 2024-03-12
• flowise-componentsnpmLLM dependency since 2023-04-10 · 1 tracked dependent

Topics

• Model Context Protocol

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