# 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.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** GHSA-c9gw-hvqq-f33r

## 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 (Improper Neutralization of Special Elements used in an OS Command)

## 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 | Ecosystem | 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: Flowiseai Flowise.

## How do I fix CVE-2026-40933?

Upgrade flowise to 3.1.0 or later.

## 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](https://insights.sbomify.com/CVE-2025-71338/): Flowise through 2.2.7 - Arbitrary File Write to Remote Code Execution via document-store API (critical 10.0)
- [CVE-2025-61913](https://insights.sbomify.com/CVE-2025-61913/): Flowise is vulnerable to arbitrary file read, arbitrary file write (critical 10.0)
- [CVE-2025-59528](https://insights.sbomify.com/CVE-2025-59528/): Flowise has Remote Code Execution vulnerability (critical 10.0)
- [CVE-2026-52098](https://insights.sbomify.com/CVE-2026-52098/): Code injection in n/a (critical 9.8)
- [CVE-2025-58434](https://insights.sbomify.com/CVE-2025-58434/): Flowise Cloud and Local Deployments have Unauthenticated Password Reset Token Disclosure that Leads to Account Takeover (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40933 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40933 exists.

Affected packages and fixed versions:
- flowise (npm): affected all versions; fixed in 3.1.0
- flowise (npm): affected all versions; fixed in 3.1.0
- flowise-components (npm): affected all versions; fixed in 3.1.0
- flowise-components (npm): affected all versions; fixed in 3.1.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40933/ (Markdown: https://insights.sbomify.com/CVE-2026-40933/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40933
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40933
- OSV: https://osv.dev/vulnerability/CVE-2026-40933

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40933/
Summaries are generated and may contain mistakes; the official description above is the record.