---
id: CVE-2026-58057
title: Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity
summary: >-
  Flowise before 3.1.3 validates Custom MCP stdio environment variables against
  a denylist using a case-sensitive comparison, so on Windows, where environment
  names are case-insensitive, supplying 'node_options' bypasses the NODE_OPTIONS
  d…
severity: medium
cvss: 5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L'
cvssSource: cna
cwe:
  - CWE-178
vendor: Flowise
product: Flowise
affected:
  - Flowise < 3.1.3
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-29T12:23:43.023783Z'
exploitAvailable: true
published: '2026-06-28'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:06:43.889Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-58057'
references:
  - url: >-
      https://github.com/bikini/exploitarium/tree/main/flowise-mcp-env-case-bypass-poc
    label: Proof of Concept
  - url: 'https://github.com/FlowiseAI/Flowise/pull/6471'
    label: 'Fix (PR #6471, 3.1.3)'
  - url: >-
      https://www.vulncheck.com/advisories/flowise-custom-mcp-environment-variable-denylist-bypass-via-case-sensitivity
    label: >-
      VulnCheck Advisory: Flowise - Custom MCP Environment Variable Denylist
      Bypass via Case Sensitivity
tags:
  - cve.org
  - exploit-available
epss: 0.01556
epssPercentile: 0.75351
exploits:
  exploitdb: true
  github: 1
  githubRepos:
    - 'https://github.com/CerberusMrXi/Flowise-CVE-2026-58057-exploit'
  checkedAt: '2026-11-08T14:51:57.334Z'
ingestedAt: '2026-11-08T14:51:22.311Z'
---

## Overview

Flowise before 3.1.3 validates Custom MCP stdio environment variables against a denylist using a case-sensitive comparison, so on Windows, where environment names are case-insensitive, supplying 'node_options' bypasses the NODE_OPTIONS denylist entry. An authenticated user who can configure a Custom MCP node can thereby inject NODE_OPTIONS --require and execute arbitrary code in the Flowise server context.

## Affected

- `Flowise < 3.1.3`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.