cvedb.io
CVE-2026-40933
CRITICAL · CVSS 9.9
EPSS exploitation probability: 0%
Published 2026-04-21T22:16:19.383 · Last modified 2026-06-17T10:45:54.440

Summary

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.0, due to unsafe serialization of stdio commands in the MCP adapter, an authenticated attacker can add an MCP stdio server with an arbitrary command, achieving command execution. The vulnerability lies in a bug in the input sanitization from the “Custom MCP” configuration in http://localhost:3000/canvas - where any user can add a new MCP, when doing so - adding a new MCP using stdio, the user can add any command, even though your code have input sanitization checks such as validateCommandInjection and validateArgsForLocalFileAccess, and a list of predefined specific safe commands - these commands, for example "npx" can be combined with code execution arguments ("-c touch /tmp/pwn") that en

Affected products

flowiseai — flowise

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.