CVE-2026-5027
CVSS 8.8 HIGH: the 'POST /api/v2/files' endpoint does not sanitize the 'filename' parameter from the multipart form data, allowing… EPSS 36% (98th percentile).
Vulnerabilities & Exploits · Web App Attack
Langflow is a control plane for AI app instances, not just a low-code builder, and this flaw gives a stranger a way to write on the server from one unauthenticated request. In practice, the trust break is in the file endpoint: anonymous access gets a session by default, and the endpoint accepts a filename it should never trust from the requester.
The bug is CVE-2026-5027, a path traversal issue in POST /api/v2/files. Tenable says the endpoint does not sanitize the filename parameter, and VulnCheck says the flaw is being exploited in the wild; reporting also ties roughly 7,000 Langflow instances to public exposure, most in North America.
That makes exposed Langflow installs a foothold into the AI app infrastructure itself, not just a development console. File write is the immediate break, and it can be enough to move into remote code execution depending on what the server will run or load next.
3 sources · Jun 11
CVSS 8.8 HIGH: the 'POST /api/v2/files' endpoint does not sanitize the 'filename' parameter from the multipart form data, allowing… EPSS 36% (98th percentile).
SecurityWeek
Hackers Exploit Langflow Vulnerability for Remote Code Execution
Disclosed in March, the security defect enables unauthenticated attackers to write files to arbitrary locations on the system.
originalThe Hacker News
Langflow Vulnerability CVE-2026-5027 Exploited for Unauthenticated RCE
CVE-2026-5027 lets attackers abuse Langflow path traversal, exposing 7,000 AI app instances to file-write attacks.
originalBleepingComputer
Path traversal flaw in AI dev platform Langflow exploited in attacks
Attackers are actively exploiting CVE-2026-5027, a high-severity path traversal vulnerability in the AI development platform Langflow, to write arbitrary files on exposed servers.
originalPart of the PlainSec briefing for 2026-06-11
Every edition of this story: Langflow Bug Turns AI Builder Into Server Write Surface