CVE-2026-91931 Flowise before 3.1.4 Remote Code Execution via Custom MCP npx
Authenticated attackers can execute arbitrary code on Flowise servers by injecting malicious npm packages into the Custom MCP node configuration.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-91931?
CVE-2026-91931 is a critical command injection vulnerability in FlowiseAI Flowise, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-78
Which versions are affected by CVE-2026-91931?
How do I fix CVE-2026-91931?
No fix has been published for CVE-2026-91931 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-91931 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91931 exists.
Sources
Also known as GHSA-q5vh-j6x8-9f53, GHSA-vcwp-f9rq-3887.