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CVE-2026-3611

Critical Vulnerability: CVE-2026-3611 — honeywell — iq4e_firmware, iq4e

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 a

Friday, June 5, 2026honeywellVulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-3611 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.

Affected technology: iq4e_firmware, iq4e, iq412_firmware, iq412, iq422_firmware, plus 5 other product variants.

Executive Summary

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.

Why It Matters

CVE-2026-3611 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 10/10

Affected Technologies

Vendors: honeywell

Products: iq4e_firmware, iq4e, iq412_firmware, iq412, iq422_firmware, iq422, iq4nc_firmware, iq4nc, iq41x_firmware, iq41x

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-3611.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2026-3611 and similar vulnerabilities.

    References & Sources

  • https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-069-03.json
  • https://www.cisa.gov/news-events/ics-advisories/icsa-26-069-03
  • https://www.honeywell.com/us/en/contact

    • How Vulnios Detects This

    Vulnios scans for this vulnerability using Trivy and Grype for SBOM-based CVE matching and Vulnios CVE feed continuous monitoring against your asset inventory. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.

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    Affected Products

    iq4e_firmwareiq4eiq412_firmwareiq412iq422_firmwareiq422iq4nc_firmwareiq4nciq41x_firmwareiq41x

    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2026-3611?

    CVE-2026-3611 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. 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 d

    Am I affected?

    Check whether your environment runs iq4e_firmware, iq4e, iq412_firmware, iq412, iq422_firmware. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.

    How urgent is the response?

    Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.

    How do I remediate?

    Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.

    Where can I track exploitation activity?

    Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2026-3611. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.

    How does Vulnios help with this?

    Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.

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