A critical vulnerability in Flowise allows authenticated attackers to achieve remote code execution through the upload of malicious JavaScript files.

The application fails to properly restrict file upload types within the Chatflow configuration, allowing an authenticated attacker to bypass frontend restrictions and upload arbitrary JavaScript files. This flaw enables the persistent storage of malicious Node.js web shells on the host server.

The ability to execute arbitrary code on the host server poses a severe threat to the confidentiality, integrity, and availability of the entire environment. An attacker could gain full control over the Flowise instance, potentially leading to data exfiltration, lateral movement within the network, or the compromise of sensitive credentials associated with the LLM workflows. With a CVSS score of 7.1, this high severity vulnerability necessitates immediate attention to prevent system takeover.

Immediate Action: Update Flowise to version 3.1.0 or later to apply the necessary file type validation and security patches.

Proactive Monitoring: Review web server logs for suspicious POST requests to configuration endpoints and monitor for the creation of unexpected JavaScript files within the application directory.

Compensating Controls: Implement a Web Application Firewall (WAF) to block requests containing suspicious MIME types or unauthorized file extensions until the patch can be applied.

Public Exploit Available: Unknown.

The risk of remote code execution via arbitrary file upload is significant and requires urgent remediation. Administrators must prioritize updating to version 3.1.0 to close the attack vector. If an immediate update is not feasible, restrict access to the Chatflow configuration interface to trusted users only and employ strict egress filtering to prevent potential web shells from communicating with external command and control servers.