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CVE-2026-3611: Honeywell Iq4e Firmware Missing Authentication (CVSS 10)

CVE-2026-3611 is a critical severity missing authentication in Honeywell Iq4e Firmware with a CVSS score of 10. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Last updated: Jun 17, 2026

Quick answer

Direct answer

CVE-2026-3611 is a critical severity missing authentication in Honeywell Iq4e Firmware with a CVSS score of 10. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Risk scores

CVSS base score
10CRITICAL
EPSS probability
1.03%
Higher than 63 percent of all CVEs
CISA KEV
Not listed
CVSS metricWhat it means
Attack vector (AV:N)Network: reachable remotely
Attack complexity (AC:L)Low complexity
Attack requirements (AT:N)No attack requirements
Privileges required (PR:N)No privileges required
User interaction (UI:N)No user interaction
Confidentiality (VC:H)High confidentiality impact
Integrity (VI:H)High integrity impact
Availability (VA:H)High availability impact

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

About Honeywell Iq4e Firmware

CVE-2026-3611 affects Honeywell Iq4e Firmware, a product from Honeywell. Before acting, confirm where Honeywell Iq4e Firmware runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: 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 weakness class is Missing Authentication. A critical function can be used without logging in.

Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Affected versions and timeline

FieldDetail
ProductHoneywell Iq4e Firmware
Affected versionsIq4e Firmware before 3.30; Iq412 Firmware before 3.30; Iq422 Firmware before 3.30; Iq4nc Firmware before 3.30; Iq41x Firmware before 3.30
PublishedMar 12, 2026
Last modifiedJun 17, 2026
Added to CISA KEVNot listed
Assigning CNAics-cert@hq.dhs.gov

How to detect it

  • Inventory every instance of Honeywell Iq4e Firmware and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Honeywell Iq4e Firmware named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Honeywell Iq4e Firmware to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeRank using EPSS and CVSS together with asset exposure and business impact.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-3611 is a critical severity missing authentication in Honeywell Iq4e Firmware with a CVSS score of 10. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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