CVE-2026-40933
CVE-2026-40933 · Flowise: Authenticated RCE Via MCP Adapters
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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.
CVSS 10.0 · Critical · EPSS 12.0% · Fix available
- Published
- Updated
Stack: node
Affected products and versions
flowise
- Versions
- < 3.1.0: Affected
No fix published
flowise-components
- Versions
- < 3.1.0: Affected
No fix published
flowise npm
- Affected ranges
- SEMVER: < 3.1.0
Update to 3.1.0
flowise-components npm
- Affected ranges
- SEMVER: < 3.1.0
Update to 3.1.0
Original sources
- https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r
- https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem
- https://www.ox.security/blog/the-mother-of-all-ai-supply-chains-critical-systemic-vulnerability-at-the-core-of-the-mcp
- https://nvd.nist.gov/vuln/detail/CVE-2026-40933