IBM Langflow OSS versions 1.0.0 through 1.10.3 contain a path traversal flaw in the Knowledge Bases API. User‑provided knowledge base names are incorporated directly into filesystem paths without sanitization. An authenticated attacker can craft a request to the POST /api/v1/knowledge_bases endpoint to create arbitrary directories and write files anywhere on the server’s filesystem. This flaw is a classic example of CWE‑22, which can enable persistence of malicious content or execution of arbitrary code if executable files are written to a location reachable by the web server.

The vulnerability affects IBM Langflow OSS. All installations running versions 1.0.0 up to and including 1.10.3 are impacted. The affected releases are listed in the CNA data and correspond to the Common Platform Enumeration strings for 1.0.0 and 1.10.3.

The CVSS score of 5.4 indicates a moderate severity. The EPSS score is not available, and the vulnerability is not listed in the CISA KEV catalog, suggesting it is not known to be actively exploited at large scale. However, the requirement for authenticated access to the Knowledge Bases API means an attacker who compromises a legitimate user’s credentials can immediately create files on the server. The potential impact includes unauthorized writes, config tampering, or code execution if files are placed in a web‑executable directory. The attack vector is through the public API, but only after authentication, and the flaw does not allow unauthenticated exploitation.