Attackers are actively exploiting CVE-2026-5027, a high-severity path traversal vulnerability in Langflow, an open-source AI development platform with over 149,000 GitHub stars. The flaw in the POST /api/v2/files endpoint allows unauthenticated attackers to write arbitrary files to the server filesystem by manipulating the filename parameter with path traversal sequences. Because Langflow enables unauthenticated auto-login by default, no credentials are needed to exploit the endpoint. Tenable discovered and disclosed the flaw after the Langflow team failed to respond; patches were released in langflow-base 0.8.3 and Langflow 1.9.0. VulnCheck honeypots have detected active exploitation, and Censys scans show roughly 7,000 publicly exposed instances. This follows a pattern of multiple Langflow CVEs being exploited in 2025-2026, including one linked to the Iranian threat group MuddyWater. Users are urged to upgrade to version 1.10.0.
