Flowise SSRF Bypass: Internal Network at Risk

The National Vulnerability Database has detailed CVE-2026-41270, a critical Server-Side Request Forgery (SSRF) protection bypass in Flowise, a drag-and-drop UI for building custom LLM flows. Prior to version 3.1.0, Flowise’s Custom Function feature allowed authenticated users to circumvent existing SSRF controls. While the application uses HTTP_DENY_LIST for axios and node-fetch libraries, it leaves built-in Node.js http, https, and net modules unprotected within its NodeVM sandbox.

This oversight means an authenticated attacker can leverage these unmonitored modules to bypass the intended SSRF protections. The implications are significant: direct access to internal network resources becomes possible. This includes sensitive targets like cloud provider metadata services, which often contain credentials and configuration data critical for further compromise. The vulnerability carries a CVSS score of 7.1 (HIGH), underscoring its potential impact.

For defenders, this means a clear, direct path to internal systems if Flowise instances are exposed and unpatched. The attacker’s calculus is simple: gain authenticated access to Flowise, then exploit this bypass to pivot deeper into the network. This isn’t theoretical; it’s a blueprint for lateral movement and privilege escalation. The fix is in version 3.1.0, and immediate patching is non-negotiable for anyone running Flowise.