What’s Vulnerable › Vulnerabilities

CVE-2026-58057: Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity

• Severity: medium (CVSS 5.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-06-28 · updated 2026-10-25
• Weakness: CWE-178

Description

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 products

• FlowiseAI Flowise: before 3.1.3 — fixed in 3.1.3

How to fix

Upgrade to a fixed version: FlowiseAI Flowise 3.1.3. Check the vendor advisory for mitigations.

References

• https://github.com/FlowiseAI/Flowise/pull/6471
• https://github.com/bikini/exploitarium/tree/main/flowise-mcp-env-case-bypass-poc
• https://www.vulncheck.com/advisories/flowise-custom-mcp-environment-variable-denylist-bypass-via-case-sensitivity

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