{"id":"CVE-2026-3611","aliases":["EUVD-2026-11706","GHSA-3p4g-vg78-jqrv"],"status":"published","title":"Honeywell IQ4x BMS Controller Missing authentication for critical function","description":"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.","severity":{"version":"4.0","score":10,"vector":"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","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.06298,"percentile":0.93657,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":false},"cwes":["CWE-306"],"published":"2026-03-12T20:06:05Z","modified":"2026-06-17T10:43:52Z","exploits":[{"source":"pocgithub","id":"spinfosecurity/BAS-Guardian","title":"spinfosecurity/BAS-Guardian","date":"2026-08-03","url":"https://github.com/spinfosecurity/BAS-Guardian"}],"products":[{"vendor":"honeywell","product":"iq3"},{"vendor":"honeywell","product":"iq412"},{"vendor":"honeywell","product":"iq412_firmware"},{"vendor":"honeywell","product":"iq41x"},{"vendor":"honeywell","product":"iq41x_firmware"},{"vendor":"honeywell","product":"iq422"},{"vendor":"honeywell","product":"iq422_firmware"},{"vendor":"honeywell","product":"iq4e"},{"vendor":"honeywell","product":"iq4e_firmware"},{"vendor":"honeywell","product":"iq4nc"},{"vendor":"honeywell","product":"iq4nc_firmware"},{"vendor":"honeywell","product":"iqeco"}],"references":[{"url":"https://www.cisa.gov/news-events/ics-advisories/icsa-26-069-03","tags":["Third Party Advisory","US Government Resource"]},{"url":"https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-069-03.json","tags":["Issue Tracking"]},{"url":"https://www.honeywell.com/us/en/contact","tags":["Product"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-3611"},{"url":"https://github.com/advisories/GHSA-3p4g-vg78-jqrv"}],"sources":{"cve":[{"id":"CVE-2026-3611","title":"Honeywell IQ4x BMS Controller Missing authentication for critical function","description":"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.","status":"published","published":"2026-03-12T20:06:05.753Z","modified":"2026-03-30T15:26:08.604Z","cvss":[{"version":"4.0","score":10,"vector":"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","level":"critical","assessor":"cna"},{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T13:48:58.05327Z"}],"euvd":[{"id":"EUVD-2026-11706","description":"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.","status":"published","published":"2026-03-12T20:06:05Z","modified":"2026-03-30T15:26:08Z","cvss":[{"version":"4.0","score":10,"vector":"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","level":"critical"}],"updated_at":"2026-11-02T19:25:25.878486Z"}],"ghsa":[{"id":"GHSA-3p4g-vg78-jqrv","title":"The Honeywell IQ4x building management controller, exposes its full web-based HMI without...","description":"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.","status":"published","published":"2026-03-12T21:34:51Z","modified":"2026-03-12T21:35:01Z","cvss":[{"version":"4.0","score":10,"vector":"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","level":"critical"},{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T15:06:35.870837Z"}],"nvd":[{"id":"CVE-2026-3611","description":"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.","status":"published","published":"2026-03-12T21:16:27.693Z","modified":"2026-06-17T10:43:52.107Z","cvss":[{"version":"4.0","score":10,"vector":"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","level":"critical","assessor":"secondary"},{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"secondary"},{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"primary"}],"cwes":["CWE-306"],"updated_at":"2026-11-02T14:12:09.358914Z"}]}}