The vulnerability arises from an unauthenticated file upload endpoint that accepts files of unlimited size. An attacker can mine the server's disk with arbitrary data, exhausting storage and causing a denial of service. The response also leaks the full absolute path of the uploaded file, exposing sensitive filesystem information that could be used to facilitate further attacks Authentication (CWE‑306), Uncontrolled Resource Consumption (CWE‑400), and Information Exposure (CWE‑200).

Langflow (langflow‑ai:langflow) older than version 1.9.1. Any deployment of Langflow 1.8 unauthenticated users over the network is vulnerable.

The score of 9.3 marks this vulnerability as critical. Because no authentication is required and there are no size limits, the attack will succeed from any host able to reach the Langflow instance. The EPSS score is not available, but the clear attack surface suggests a high exploitation probability. The vulnerability has not appeared in the CISA KEV catalog yet, but its severity warrants urgent remediation. The likely attack vector is remote network access to the upload endpoint.