CVE-2026-58057: Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity
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 'nodeoptions' bypasses the NODEOPTIONS denylist entry. An authenticated user who can configure a Custom MCP node can thereby inject NODEOPTIONS --require and execute arbitrary code in the Flowise server context.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Flowiseto a version that resolves this vulnerability.Fixed in 3.1.3 - Configuration
Ensure Flowise validates Custom MCP stdio environment variables against the NODE_OPTIONS denylist using a case-insensitive comparison to prevent bypass via 'node_options' casing (issue present before 3.1.3).
Flowise - Custom MCP node environment variable validation NODE_OPTIONS denylist case-insensitive comparison = case-insensitive (Windows-safe)
Event History
Frequently Asked Questions
What is the severity of CVE-2026-58057?
CVE-2026-58057 has a medium severity rating of 5.
How do I fix CVE-2026-58057?
To fix CVE-2026-58057, upgrade Flowise to version 3.1.3 or later.
What type of environment does CVE-2026-58057 affect?
CVE-2026-58057 affects the Flowise application running on Windows due to its case-insensitive environment variable handling.
What is the risk associated with CVE-2026-58057?
CVE-2026-58057 has a risk score of 39, indicating potential exploitation under specific conditions.
Who can exploit CVE-2026-58057?
An authenticated user with access to configure Custom MCP environment variables can exploit CVE-2026-58057.