CVE-2026-40933: Flowise is a drag & drop user interface to build a customized large language model flow

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CRITICAL 9.9UPGRADE

CVE-2026-40933 is a critical-severity flaw (CVSS 9.9) affecting flowise. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 do

Why this priority

Critical severity
EPSS top 4%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	9.9 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	12.0% (top 4%)
CISA exploited list	No
Weakness	CWE-78
Published	2026-04-21
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: flowiseai

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-21 22:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

flowiseai flowise UPGRADE

Affected: < 3.1.0

Fixed in: 3.1.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy flowise || rpm -q flowise || flowise --version

2. UPGRADE to 3.1.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade flowise

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade flowise

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

npm · flowise · FIXED · 3.1.0 · vulnerable: <= 3.0.13 · source

npm install flowise@">=3.1.0" npm ls flowise

npm · flowise-components · FIXED · 3.1.0 · vulnerable: <= 3.0.13 · source

npm install flowise-components@">=3.1.0" npm ls flowise-components

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40933?

flowise: upgrade to 3.1.0. Exact commands for each OS are on this page.

Is CVE-2026-40933 being exploited?

CVE-2026-40933 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40933 affect?

CVE-2026-40933 affects flowise. Severity is critical (CVSS 9.9). 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 arbitra

How urgent is CVE-2026-40933?

Priority 64/100. Critical severity; EPSS top 4%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2026-41268 CRITICAL 9.8 UPGRADE Flowise is a drag & drop user interface to build a customized large language model flow
CVE-2026-41276 CRITICAL 9.8 UPGRADE Flowise is a drag & drop user interface to build a customized large language model flow
CVE-2026-41265 CRITICAL 9.8 UPGRADE Flowise is a drag & drop user interface to build a customized large language model flow
CVE-2026-41137 HIGH 8.8 UPGRADE Flowise is a drag & drop user interface to build a customized large language model flow
CVE-2026-41272 HIGH 7.1 UPGRADE Flowise is a drag & drop user interface to build a customized large language model flow

References

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