ABB EIBPORT V3 KNX building management systems are affected by a cross-site scripting vulnerability (CVE-2021-22291) with CVSS score 8.0. The vulnerability allows attackers to access sensitive information and change device configuration by obtaining session IDs. Affected versions include EIBPORT V3 KNX models below version 3.9.2. ABB has released firmware updates to address the vulnerability. The flaw affects critical manufacturing and IT infrastructure worldwide, with session management failing to maintain secure sessions.