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Fencer Vulns
critical 10.0

CVE-2026-3611 json

Honeywell IQ4x BMS Controller Missing authentication for critical function

published 2026-03-12 7 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-11706

cvss
10.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
6.3%
EPSS 6.3% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

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.

Patch / fix

  • honeywell iq4e_firmware 3.30
  • honeywell iq412_firmware 3.30
  • honeywell iq422_firmware 3.30
  • honeywell iq4nc_firmware 3.30
  • honeywell iq41x_firmware 3.30

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-26-069-03 updated cvss 9.8

Honeywell IQ4 Series BMS Controller (Update A)

  • Honeywell IQ4E Firmware <v3.30 Honeywell IQ4NC Firmware <v3.30 Honeywell IQ41x Firmware <v3.30 Honeywell IQ412 Firmware <v3.30 Honeywell IQ422 Firmware <v3.30
    affected: mitigation “Honeywell recommends that users with affected products take the following steps:” partners.trendcontrols.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
7 mo ago

Exploit prediction

6.30% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 10.0 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
CNA 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CNA 4.0 10.0 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
NVD 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Honeywell IQ4E
  • Honeywell IQ412
  • Honeywell IQ422
  • Honeywell IQ4NC
  • Honeywell IQ41x
  • Honeywell IQ3
  • Honeywell IQECO

Classification

Weakness
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.