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VulnerabilityPublished Updated

CVE-2026-3611: Honeywell IQ4E · Missing Authentication

Affects Honeywell IQ4ESource CVE Database V5

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Not known to be exploited · CVSS 10.0 Critical.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
10.0Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
5.7% chance of exploitation in 30 days – higher than 93% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
HoneywellIQ4EAffected
  • ≥ v3.50_3.44, ≤ 4.36 (build 4.3.7.9)
Fixed in–
HoneywellIQ412Affected
  • ≥ v3.50_3.44, ≤ 4.36 (build 4.3.7.9)
Fixed in–
HoneywellIQ422Affected
  • ≥ v3.50_3.44, ≤ 4.36 (build 4.3.7.9)
Fixed in–
HoneywellIQ4NCAffected
  • ≥ v3.50_3.44, ≤ 4.36 (build 4.3.7.9)
Fixed in–
HoneywellIQ41xAffected
  • ≥ v3.50_3.44, ≤ 4.36 (build 4.3.7.9)
Fixed in–
HoneywellIQ3Affected
  • ≥ v3.50_3.44, ≤ 4.36 (build 4.3.7.9)
Fixed in–

AI-suggested

Organizations should immediately verify if their Honeywell IQ4E controllers are running affected versions (v3.50_3.44) and assess exposure of the HTTP interface to untrusted networks. Network segmentation and firewall rules should be implemented to restrict access to the controller's web interface to trusted administrators only. If possible, disable or isolate devices in factory-default configurations until proper user modules and authentication are configured. Honeywell should be contacted for official patches or firmware updates addressing this vulnerability; until then, manual configuration of user accounts should be performed in a secure environment. Monitoring network traffic for unauthorized access attempts to the U.htm page can help detect exploitation attempts. Additionally, organizations should implement multi-factor authentication and strong password policies once user modules are enabled. Incident response plans should include procedures for recovery if unauthorized administrative accounts are created.

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.

References

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