CVE-2026-40933 Flowise: Authenticated RCE Via MCP Adapters
An authenticated attacker can achieve remote code execution by injecting malicious commands into the MCP stdio server configuration.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40933?
CVE-2026-40933 is a critical command injection vulnerability in Flowiseai Flowise, published on 21 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
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.
Weakness: CWE-78
Which versions are affected by CVE-2026-40933?
4 open source packages ship an affected version, including flowise and flowise-components. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
flowise npm | All versions | 3.1.0 |
flowise npm | All versions | 3.1.0 |
flowise-components npm | All versions | 3.1.0 |
flowise-components npm | All versions | 3.1.0 |
Products include Flowiseai Flowise.
How do I fix CVE-2026-40933?
Upgrade flowise to 3.1.0 or later.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-40933 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40933 exists.
Other vulnerabilities in Flowiseai Flowise
- CVE-2025-71338 Flowise through 2.2.7 - Arbitrary File Write to Remote Code Execution via document-store API
- CVE-2025-61913 Flowise is vulnerable to arbitrary file read, arbitrary file write
- CVE-2025-59528 Flowise has Remote Code Execution vulnerability
- CVE-2026-52098 Code injection in n/a
- CVE-2025-58434 Flowise Cloud and Local Deployments have Unauthenticated Password Reset Token Disclosure that Leads to Account Takeover
Sources
Also known as GHSA-c9gw-hvqq-f33r.