A directory traversal flaw exists in the knowledge base creation endpoint of langflow. The endpoint accepts a filename parameter and forwards it directly into the host file creation routine without enforcing a boundary, allowing an attacker to provide absolute paths. As a result, an attacker can write or overwrite any file on the filesystem that the application’s user has permission to modify, potentially compromising code execution, data integrity, or system configuration.

langflow‑ai Langflow version 1.8.4 is affected. The vulnerability resides in src/backend/base/langflow/api/v1/knowledge_bases.py. No other vendors or products are listed.

The attack vector is remote, via HTTP requests to the public knowledge base creation route. Because the flaw permits arbitrary file write, a successful exploit could lead to the creation of malicious executables or alteration of critical files, resulting in full system compromise. The CVSS score is 7.5, indicating a high severity level. The EPSS score is < 1%, and the vulnerability is not listed in CISA’s KEV catalog, so the current exploit probability is low but non-zero. Until a fix is applied, the risk remains significant.