The vulnerability in Flowise lies in the file upload configuration for chatflow definitions. Prior to version 3.1.0 the application allowed the MIME type application/javascript to be selected, which bypassed frontend restrictions and enabled an attacker to upload .js files. These files can contain Node.js web‑shell code that remains stored on the server, allowing an attacker to execute arbitrary code on the host. The flaw is a classic instance of CWE‑434, an unvalidated file type upload that leads to remote code execution.

Flowise by FlowiseAI is affected. All releases prior to 3.1.0 are vulnerable, including any 3.x or 2.x variants bundled with the drag-and-drop interface for large‑language‑model workflows.

The CVSS score of 7.1 indicates a serious risk, while the EPSS score of < 1% suggests that, at the time of this analysis, exploitation likelihood is low but not negligible. The vulnerability is not yet listed in CISA’s KEV catalog. An attacker would typically exploit the flaw by accessing the chatflow file upload interface, selecting the allowed MIME type, and uploading a crafted .js file. The attack requires only that the upload endpoint be reachable; authentication is not strictly required if the endpoint is publicly exposed. The reach of the vulnerability means that compromised files can persist on the server, allowing remote code execution on the machine hosting Flowise.