Vulnerability · Published Apr 21, 2026 · Assigned by GitHub_M
CVE-2026-40933Flowise: Authenticated RCE Via MCP Adapters
Critical 10.0
In plain English
A critical-severity OS command injection in Flowise from FlowiseAI. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 12.0% (higher than 96% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 “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 enable direct code execution on the underlying OS. This vulnerability is fixed in 3.1.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | flowise | 3.1.0 | GHSA-c9gw-hvqq-f33r |
| npm | flowise-components | 3.1.0 | GHSA-c9gw-hvqq-f33r |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| FlowiseAI | Flowise | < 3.1.0 |
| FlowiseAI | flowise-components | < 3.1.0 |
Weakness: CWE-78 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
References
- https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r x_refsource_CONFIRM
- https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem x_refsource_MISC
- https://www.ox.security/blog/the-mother-of-all-ai-supply-chains-critical-systemic-vulnerability-at-the-core-of-the-mcp x_refsource_MISC