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Vulnerabilities

Vulnerability · CVE-2026-3611

The Honeywell IQ4x building management controller, exposes its full web-based HMI without authentication in its factory-default configuration.

Published Mar 12, 2026 · catalog updated Jun 17, 2026 · iq4e firmware

Check if you run it

No confirmed exploitation is on record for CVE-2026-3611. EPSS is 1.03%. Act only if a listed version of iq4e firmware is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical10.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.03%
Remediation
Advisory link
Affected products
cpe honeywell/iq412 firmware · cpe honeywell/iq41x firmware · cpe honeywell/iq422 firmware · cpe honeywell/iq4e firmware · cpe honeywell/iq4nc firmware

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe honeywell/iq412 firmwareversion unspecified
  • cpe honeywell/iq41x firmwareversion unspecified
  • cpe honeywell/iq422 firmwareversion unspecified
  • cpe honeywell/iq4e firmwareversion unspecified
  • cpe honeywell/iq4nc firmwareversion unspecified

How to fix CVE-2026-3611

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-3611. EPSS is 1.03%. Act only if a listed version of iq4e firmware is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-306: Missing Authentication for Critical Function. EPSS 1.03%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 12, 2026 · NIST NVD

    Detected

    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

  2. Jun 17, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-3611

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-3611

    30-day exploitation probability 1.0%

    first.org
  • NIST NVDVulnerability recordCVE-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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.