CVE-2026-3611 — Honeywell IQ4x BMS Controller Missing authentication for critical function
The Honeywell IQ4x building management controller, exposes its full web-based HMI without authentication in its factory-default configuration. With no user module configured, se…
Published: 2026-03-12 · CVSS: 10.0 · CVSS 4.0
The Honeywell IQ4x building management controller, exposes its full web-based HMI without authentication in its factory-default configuration. With no user module configured, security is disabled by design and the system operates under a System Guest (level 100) context, granting read/write privileges to any party able to reach the HTTP interface. Authentication controls are only enforced after a web user is created via U.htm, which dynamically enables the user module. Because this function is accessible prior to authentication, a remote user can create a new account with administrative read/write permissions enabling the user module and imposing authentication under attacker-controlled credentials. This action can effectively lock legitimate operators out of local and web-based configuration and administration.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7