Honeywell IQ4x BMS Controller Missing authentication for critical function

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Summary

CVECVE-2026-3611
StatePUBLISHED
Assignericscert
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-12 21:16:27 UTC
Updated2026-06-05 19:39:29 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v4.0 10 CRITICAL from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-306 | CWE-306 CWE-306 Missing authentication for critical function

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary10CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/C...
4.0CNACVSS10CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
3.1[email protected]Primary10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1[email protected]Secondary10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1CNACVSS10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
High
Integrity
High
Availability
High
Sub Conf.
High
Sub Integrity
High
Sub Availability
High

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Hardware Honeywell Iq412 - All All All
Operating System Honeywell Iq412 Firmware All All All All
Hardware Honeywell Iq41x - All All All
Operating System Honeywell Iq41x Firmware All All All All
Hardware Honeywell Iq422 - All All All
Operating System Honeywell Iq422 Firmware All All All All
Hardware Honeywell Iq4e - All All All
Operating System Honeywell Iq4e Firmware All All All All
Hardware Honeywell Iq4nc - All All All
Operating System Honeywell Iq4nc Firmware All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Honeywell IQ4E affected v3.50_3.44 4.36 (build 4.3.7.9) custom Not specified
CNA Honeywell IQ412 affected v3.50_3.44 4.36 (build 4.3.7.9) custom Not specified
CNA Honeywell IQ422 affected v3.50_3.44 4.36 (build 4.3.7.9) custom Not specified
CNA Honeywell IQ4NC affected v3.50_3.44 4.36 (build 4.3.7.9) custom Not specified
CNA Honeywell IQ41x affected v3.50_3.44 4.36 (build 4.3.7.9) custom Not specified
CNA Honeywell IQ3 affected v3.50_3.44 4.36 (build 4.3.7.9) custom Not specified
CNA Honeywell IQECO affected v3.50_3.44 4.36 (build 4.3.7.9) custom Not specified

References

ReferenceSourceLinkTags
www.honeywell.com/us/en/contact [email protected] www.honeywell.com Product
github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-06... [email protected] github.com Issue Tracking
www.cisa.gov/news-events/ics-advisories/icsa-26-069-03 [email protected] www.cisa.gov Third Party Advisory, US Government Resource
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Gjoko Krstic of Zero Science reported this vulnerability to Honeywell. (en)

Additional Advisory Data

Workarounds

CNA: 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).

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