CVE-2026-58057

LowPublished

Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity

Published: Jun 28, 2026
Updated: Jun 29, 2026
Assigning CNA: VulnCheck
Evidence observed: Jul 7, 2026

Primary CVSS

2.3/ 10Low

nvd · CVSS 4.0

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS probability estimate

1.6%

Low · next 30 days

Percentile: 73.7%
Model date: Sep 21, 2026

EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.

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 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.

Sources

Flowise-CVE-2026-58057-exploitExploit
Flowise Windows RCE exploit for CVE-2026-58057. Bypasses environment variable validation via case-sensitive flaw. Uses node_options to inject arbitrary code through MCP stdio. Supports reverse shell, persistence, file upload, credential dumping. For authorized security testing only.
Flowise 3.1.3 - arbitrary code executionExploit
banyamer · multiple · Jul 7, 2026

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