Public proof of conceptFix available

CVE-2026-40933

Q: Is CVE-2026-40933 actively exploited?

A proof-of-concept exploit exists for CVE-2026-40933, but active exploitation has not been confirmed at this time.

Q: What is the CVSS score for CVE-2026-40933?

CVE-2026-40933 has a CVSS v3 base score of 9.9 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

A public proof of concept exists; no exploitation attested.

Published2026-04-21
Fixed in3.1.0
WeaknessCWE-78

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2026-04-2122:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-40933?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-40933?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Flowiseai flowise

Branch	Affected	Fixed in	Source
3.1	< 3.1.0	3.1.0	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Flowiseai flowise to 3.1.0

Advisories and patches

github.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionpoc2026-04-22
OpenCVESSVC decisionpoc—
CNACVSS 3.19.9read 2026-10-23
CNAweakness (CWE)CWE-78read 2026-10-23
FIRST EPSSEPSS score1.3 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Published: 2026-04-21
Last Modified: 2026-06-17
NVD status: Analyzed

Frequently asked questions

What is CVE-2026-40933?

Is CVE-2026-40933 actively exploited?

A proof-of-concept exploit exists for CVE-2026-40933, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-40933?

CVE-2026-40933 has a CVSS v3 base score of 9.9 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

Hear about the next vulnerability in your software

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this product CISA KEV additions, October 2026 Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database