Path Traversal Flaw in Langflow Actively Exploited

Threat actors are now leveraging CVE-2026-5027, a high-severity path traversal vulnerability in the AI development platform Langflow, to place arbitrary files onto exposed servers.

Langflow sees widespread adoption among AI teams. The open-source visual platform supports creation of AI applications, AI agents, Retrieval-Augmented Generation (RAG) systems, and MCP-based workflows through a drag-and-drop interface instead of conventional coding. The project has gathered more than 149,000 stars and 9,200 forks on GitHub.

Tenable discovered the flaw at the start of 2026. The issue lies in the platform's file upload feature that does not adequately clean user-provided filenames. "The 'POST /api/v2/files' endpoint does not sanitize the 'filename' parameter from the multipart form data, allowing an attacker to write files to arbitrary locations on the filesystem using path traversal sequences ('../')," explains Tenable, which found the bug at the beginning of the year.

Public disclosure followed months of silence from maintainers. Tenable first notified the Langflow maintainers at the start of the year and received no reply. The security firm went public with details on March 27, 2026.

Patches arrived shortly after disclosure. According to Snyk Security on March 30, 2026, the langflow-base package received a correction in version 0.8.3 while the main Langflow application was updated in release 1.9.0.

Honeypots confirm active exploitation in the wild. VulnCheck researcher Caitlin Condon reported that monitored systems have already recorded attempts to install test files on affected deployments. "Because Langflow enables unauthenticated auto-login by default, no credentials are required to reach the vulnerable endpoint, and a single unauthenticated request is sufficient to obtain a valid session token before proceeding with exploitation," she wrote on LinkedIn.

Roughly 7,000 instances remain publicly exposed. Data from Censys points to approximately 7,000 internet-facing Langflow deployments, although those figures incorporate historical records spanning the past 12 months and might overstate the count of currently reachable systems. The attacks follow earlier campaigns this year against other Langflow issues such as CVE-2026-0770, CVE-2026-21445, and CVE-2026-33017.

Langflow users should upgrade immediately. Version 1.10.0 became available earlier today.