CVE-2026-46442

Flowise, an open-source drag-and-drop builder for LLM workflows, lacks route-level authorization on POST /api/v1/node-custom-function in versions before 3.1.2, allowing any authenticated user or API key to submit arbitrary JavaScript to the Custom JS Function node. When the E2B_APIKEY environment variable is not configured — described as the common deployment case — the submitted JavaScript runs in a local NodeVM sandbox, which can be escaped to reach the host process object and execute system commands via child_process. An attacker with any valid credentials or API key therefore gains remote code execution on the Flowise server host under the application's privileges. All self-hosted Flowise deployments prior to 3.1.2 that expose the API to non-administrative users or API keys are affected, especially those without E2B sandboxing enabled. No confirmed in-the-wild exploitation is reported yet (not in CISA KEV), but a public advisory with a proof of concept exists, and EPSS assigns a 36.3% probability of exploitation within 30 days (98th percentile).

What to do: Upgrade to Flowise 3.1.2 or later. As interim mitigations, configure E2B_APIKEY so custom JavaScript runs in the E2B cloud sandbox instead of the local NodeVM, and restrict access to POST /api/v1/node-custom-function and API-key issuance to trusted administrative users. Given the high EPSS score and public proof of concept, prioritize patching internet-exposed instances and audit existing API keys for signs of unauthorized use.