Vulnerability Details CVE-2026-3611
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 43.5%
CVSS Severity
CVSS v3 Score 10.0
References
Products affected by CVE-2026-3611
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cpe:2.3:h:honeywell:iq412:-
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cpe:2.3:h:honeywell:iq41x:-
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cpe:2.3:h:honeywell:iq422:-
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cpe:2.3:h:honeywell:iq4e:-
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cpe:2.3:h:honeywell:iq4nc:-
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cpe:2.3:o:honeywell:iq412_firmware:*
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cpe:2.3:o:honeywell:iq41x_firmware:*
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cpe:2.3:o:honeywell:iq422_firmware:*
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cpe:2.3:o:honeywell:iq4e_firmware:*
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cpe:2.3:o:honeywell:iq4nc_firmware:*