Vulnerability · Published Aug 13, 2026 · Assigned by VulnCheck

CVE-2026-73601Flowise before 3.1.3 Remote Code Execution via Custom MCP

Critical 9.0

In plain English

A critical-severity security flaw in Flowise from FlowiseAI. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.1% (higher than 66% of all known vulnerabilities).

Severity (CVSS 4.0)9.0Critical

Exploit odds (30 days)1.1%top 34.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Flowise versions before 3.1.3 contain a remote code execution vulnerability in the Custom MCP node when CUSTOM_MCP_PROTOCOL is set to stdio, allowing authenticated users to execute arbitrary commands by manipulating environment variables and command arguments. Attackers can abuse PYTHONWARNINGS and BROWSER environment variables with python3, or leverage the root working directory with node to bypass validation and execute system commands.

Affected products (as reported)

Vendor	Product	Versions
FlowiseAI	Flowise	0 – before 3.1.3
FlowiseAI	Flowise	0 – before 3.1.3

Weakness: CWE-95 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

References

GitHub Security Advisory (GHSA-g98q-rm45-q9h8) vendor-advisory
VulnCheck Advisory: Flowise before 3.1.3 Remote Code Execution via Custom MCP third-party-advisory