Langflow Path Traversal RCE Exploited in the Wild (CVE-2026-5027)

Langflow before 1.9.0; roughly 7,000 instances exposed on the public internet (Censys)

Unauthenticated arbitrary file write leading to remote code execution, for example dropping a cron job; default auto-login means a single unauthenticated request reaches the vulnerable endpoint. After disclosure by Tenable and a 1.9.0 patch, attackers weaponized the flaw and exploitation was observed in June 2026

`POST /api/v2/files` does not sanitize the multipart `filename` parameter, allowing `../` traversal to write files anywhere on the filesystem