CVE-2026-91931 PUBLISHED

Flowise before 3.1.4 Remote Code Execution via Custom MCP npx

Assigner: VulnCheck
Reserved: 15.09.2026 Published: 15.09.2026 Updated: 15.09.2026

Flowise before 3.1.4 contains a remote code execution vulnerability in the Custom MCP node that allows authenticated attackers to execute arbitrary code by supplying npx package names in the mcpServerConfig parameter. Attackers can invoke npx with attacker-controlled npm packages to execute code on the Flowise server.

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
CVSS Score: 8.5

Attack Vector	Network	Scope	Changed
Attack Complexity	High	Confidentiality Impact	High
Privileges Required	Low	Integrity Impact	High
User Interaction	None	Availability Impact	High

CVSS 3.1

CVSS Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CVSS Score: 9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	High
Attack Complexity	High	Integrity	High	Integrity	High
Attack Requirements	None	Availability	High	Availability	High
Privileges Required	Low
User Interaction	None

CVSS 4.0

Product Status

Vendor	FlowiseAI
Product	Flowise
Versions	Default: unaffected affected from 0 to 3.1.4 (excl.) Version 3.1.4 is unaffected

Vendor	FlowiseAI
Product	Flowise
Versions	Default: unaffected affected from 0 to 3.1.4 (excl.) Version 3.1.4 is unaffected

Credits

DavidCarliez reporter

References

Problem Types

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') CWE