Honeywell IQ4x BMS Controller Web-based HMI missing authentication

Summaryinfo

A vulnerability, which was classified as critical, was found in Honeywell IQ4x BMS Controller. This affects an unknown function of the component Web-based HMI. Executing a manipulation can lead to missing authentication. This vulnerability is registered as CVE-2026-3611. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability classified as critical was found in Honeywell IQ4x BMS Controller (affected version not known). This vulnerability affects some unknown functionality of the component Web-based HMI. The manipulation with an unknown input leads to a missing authentication vulnerability. The CWE definition for the vulnerability is CWE-306. The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at cisa.gov. This vulnerability was named CVE-2026-3611. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 03/15/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Honeywell

Name

• IQ4x BMS Controller

License

• commercial

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