Unpatched Langflow Path Traversal Flaw Exploited for Unauthenticated RCE

Attackers are actively exploiting CVE-2026-5027, a high-severity path traversal vulnerability in the open-source AI application platform Langflow, to write files to arbitrary locations on target systems and potentially achieve remote code execution. The flaw affects the POST /api/v2/files endpoint, where the filename parameter is not properly sanitized, and exploitation is made more severe by Langflow's default unauthenticated auto-login behavior, which lets attackers obtain a valid session token with a single unauthenticated request. VulnCheck reported observed attacks writing apparent test files to victim hosts, while Tenable identified the issue and assigned it a CVSS 8.8 score.

Internet exposure increases the risk: Censys data indicates about 7,000 Langflow instances are reachable online, with the largest concentration in North America. The exploitation report also fits a broader pattern of sustained attacker interest in Langflow, with other vulnerabilities including CVE-2026-0770, CVE-2026-21445, CVE-2026-33017, and CVE-2025-34291 also reported as exploited in 2026; the last has been linked in public reporting to the Iranian state-backed group MuddyWater. Separately, a newly disclosed flaw in Roxy-WI (CVE-2026-45556) shows a similar arbitrary file-write-to-RCE pattern on managed load balancers, but no public patch was available at publication.