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CVE-2026-3611

CRITICAL CVSS: 10.0 Published: 2026-03-12 Modified: 2026-06-17

Description

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.

Affected Platforms

Honeywell Iq4Nc FirmwareHoneywell Iq41XHoneywell Iq4E FirmwareHoneywell Iq41X FirmwareHoneywell Iq4EHoneywell Iq422 FirmwareHoneywell Iq412Honeywell Iq422Honeywell Iq412 FirmwareHoneywell Iq4Nc

Weakness Type

CWE-306

References