CVE-2026-5027

CVE-2026-5027 is a path traversal flaw (CWE-22) in the 'POST /api/v2/files' endpoint of Langflow, the open-source platform for building AI/LLM agent workflows. The endpoint fails to sanitize the 'filename' field supplied in multipart form data, so an attacker who submits a name containing '../' sequences can direct the resulting file write to arbitrary locations on the server's filesystem. The CVSS vector (network-accessible, low complexity, low-privilege account required, no user interaction) indicates an authenticated user can abuse this to overwrite or create files at attacker-chosen paths, which can compromise confidentiality, integrity, and availability — for example by overwriting configuration, credentials, or executable content that leads to code execution depending on deployment. Any organization running a self-hosted Langflow instance that exposes the files API, even to low-privileged accounts, is affected. No public proof-of-concept or confirmed in-the-wild exploitation is known for this specific CVE, and it is not yet on CISA's KEV list, but its elevated EPSS (36.1%, 98th percentile) and active exploitation of other Langflow vulnerabilities (e.g., CVE-2026-0768) suggest near-term exploitation risk.

What to do: Upgrade Langflow to the latest patched release per the vendor advisory (specific fixed version is not stated in the available data). Until patched, restrict access to /api/v2/files to trusted, authenticated users, place Langflow behind authentication/reverse-proxy filtering that strips or validates '..' sequences in multipart filenames, and avoid exposing the instance directly to the internet. Review access logs for multipart POST requests to /api/v2/files with filenames containing '../' that could indicate attempted traversal writes.