CVE-2021-27661: Johnsoncontrols f4-Snc Firmware

High severity, CVSS 8.8. EPSS: 0.8% chance of exploitation in the next 30 days.

Successful exploitation of this vulnerability could give an authenticated Facility Explorer SNC Series Supervisory Controller (F4-SNC) user an unintended level of access to the controller’s file system, allowing them to access or modify system files by sending specifically crafted web messages to the F4-SNC.

Affected products

Published 2021-07-01. Last modified 2026-06-17.