Unauthenticated controller takeover via pre-auth account creation
Published Mar 12, 2026 · Updated Mar 12, 2026
Missing authentication in Honeywell IQ4x controllers through 4.36 (build 4.3.7.9) allows remote attackers to control the web HMI. In the factory-default state, U.htm accepts creation of an administrative web user before any user module exists, then enables authentication under the new credentials. Network access to the HTTP interface is sufficient, allowing read/write control and operator lockout.
Summary
What happened
Missing authentication in Honeywell IQ4x controllers through 4.36 (build 4.3.7.9) allows remote attackers to control the web HMI. In the factory-default state, U.htm accepts creation of an administrative web user before any user module exists, then enables authentication under the new credentials. Network access to the HTTP interface is sufficient, allowing read/write control and operator lockout.
The record
- CVE
- CVE-2026-3611
- Published
- Mar 12, 2026
- Updated
- Mar 12, 2026
- Vendor
- Honeywell Technologies
- Product
- IQeco Controllers
- Classifications
- CWE-306, T1098
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 12, 2026CVE publishedPublication date reported by the CVE source.
- Mar 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=v3.50_3.44 <=4.36 (build 4.3.7.9)
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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