CVE-2026-5027 is a critical path traversal vulnerability (CVSS 8.8) in Langflow, an open-source low-code AI application builder. The flaw exists in the POST /api/v2/files endpoint where filenames in multipart form data are not sanitized, allowing directory traversal sequences to write arbitrary files anywhere on the server. Because Langflow enables unauthenticated auto-login by default, exploitation requires no credentials — a single request suffices. Approximately 7,000 publicly exposed instances have been identified via Censys scans. Active exploitation in the wild has been confirmed, with a public proof-of-concept available. Affected versions include langflow-base below 0.8.3 and Langflow up to 1.8.4. Remediation involves upgrading to Langflow 1.10.0 (or at minimum 1.9.0), disabling auto-login, restricting network exposure, and monitoring for suspicious file write activity.
