CVE-2026-3611

Honeywell IQ4x BMS Controller Missing authentication for critical function

Published Mar 12, 2026 CVSS 4.0 · 10 Critical EPSS 6.3% KEV · Not listed
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.

Remediation

Vendor Workaround

Honeywell is aware of the issue, but has not released a fix. For more information, contact Honeywell directly. [https://www.honeywell.com/us/en/contact](https://www.honeywell.com/us/en/contact).

Tracking

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Advisories

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History
Type Values Removed Values Added
First Time appeared Honeywell iq412 Firmware
Honeywell iq41x Firmware
Honeywell iq422 Firmware
Honeywell iq4e Firmware
Honeywell iq4nc Firmware
CPEs cpe:2.3:h:honeywell:iq412:-:*:*:*:*:*:*:*
cpe:2.3:h:honeywell:iq41x:-:*:*:*:*:*:*:*
cpe:2.3:h:honeywell:iq422:-:*:*:*:*:*:*:*
cpe:2.3:h:honeywell:iq4e:-:*:*:*:*:*:*:*
cpe:2.3:h:honeywell:iq4nc:-:*:*:*:*:*:*:*
cpe:2.3:o:honeywell:iq412_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:honeywell:iq41x_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:honeywell:iq422_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:honeywell:iq4e_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:honeywell:iq4nc_firmware:*:*:*:*:*:*:*:*
Vendors & Products Honeywell iq412 Firmware
Honeywell iq41x Firmware
Honeywell iq422 Firmware
Honeywell iq4e Firmware
Honeywell iq4nc Firmware
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Honeywell
Honeywell iq3
Honeywell iq412
Honeywell iq41x
Honeywell iq422
Honeywell iq4e
Honeywell iq4nc
Honeywell iqeco
Vendors & Products Honeywell
Honeywell iq3
Honeywell iq412
Honeywell iq41x
Honeywell iq422
Honeywell iq4e
Honeywell iq4nc
Honeywell iqeco
Type Values Removed Values Added
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.
Title Honeywell IQ4x BMS Controller Missing authentication for critical function
Weaknesses CWE-306
References
Metrics cvssV3_1

{'score': 10, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'}

cvssV4_0

{'score': 10, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H'}