CVE-2026-58057 | Flowise before 3.1.3 validates Custom MCP stdio environment … | CVSS 5.0 MEDIUM

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.

Metadata

CVE ID: CVE-2026-58057
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-06-28 00:55 UTC
Published: 2026-06-28 01:32 UTC
Last updated: 2026-06-28 01:32 UTC
Primary CWE: CWE-178
Improper Handling of Case Sensitivity
Vendor / Product: Flowise / Flowise
Sources: cve.org · NVD

Severity & Metrics

5.0 MEDIUM CVSS 3.1

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

Affected products (1)

Vendor	Product	Platform	Versions
Flowise	Flowise	—	0 < 3.1.3, 3.1.3

Weakness (CWE)

CWE	Source	Description
CWE-178	cna	Improper Handling of Case Sensitivity

CVSS scores (2)

Score	Severity	Version	Source	Vector
5.0	MEDIUM	3.1	cna	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
2.3	LOW	4.0	cna	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

References (3)

Proof of Concept https://github.com/bikini/exploitarium/tree/main/flowise-mcp-env-case-bypass-poc
Fix (PR #6471, 3.1.3) https://github.com/FlowiseAI/Flowise/pull/6471
VulnCheck Advisory: Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity https://www.vulncheck.com/advisories/flowise-custom-mcp-environment-variable-denylist-bypass-via-case-sensitivity