CVE-2026-40933

9.9 CRITICAL
Published: April 21, 2026 Modified: April 23, 2026
View on NVD

Description

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 β€œCustom 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 enable direct code execution on the underlying OS. This vulnerability is fixed in 3.1.0.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r
Source: security-advisories@github.com
Exploit Vendor Advisory
https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem
Source: security-advisories@github.com
Press/Media Coverage Third Party Advisory
https://www.ox.security/blog/the-mother-of-all-ai-supply-chains-critical-systemic-vulnerability-at-the-core-of-the-mcp
Source: security-advisories@github.com
Press/Media Coverage Third Party Advisory
https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Vendor Advisory

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.9 / 10.0
EPSS (Exploit Probability)
0.0%
15th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

flowiseai