IBM Langflow OSS contains a path traversal flaw in its APIRequest component. When the "Save to File" feature is enabled, filenames taken from HTTP response Content‑Disposition headers are concatenated with a temporary directory path without sanitization. An attacker who controls an external HTTP server can inject path traversal sequences (e.g., "../") into these header values, allowing them to write files to arbitrary locations under the ownership of the Langflow process. This can lead to modification or destruction of critical files, intrusion through configuration changes, and potential escalation of privileges depending on the file types written. The vulnerability is specifically a CWE‑22 "Improper Limitation of a Pathname" flaw.

The flaw is present in all IBM Langflow OSS releases from 1.0.0 up to and including 1.10.0. Attackers need the ability to supply a crafted HTTP response that Langflow will process, meaning any installation of the affected version is at risk if it interacts with untrusted external servers.

The CVSS score of 9.9 indicates critical severity, while the EPSS score of less than 1% suggests that exploitation is currently low probability. The vulnerability is not listed in CISA KEV, implying no widespread public exploitation is known. Exploitation requires an attacker to control the HTTP server that Langflow queries or to convince Langflow to download data from a malicious source; the attacker must also have local access or the ability to influence outbound requests from the Langflow environment. No public exploitation exploits were described in the advisory, but the remedy is urgent due to the potential for arbitrary file writes.