CVE-2024-5539 is an access control bypass vulnerability categorized under CWE-863 (Incorrect Authorization) affecting Automated Logic's WebCTRL and Carrier i-Vu building automation systems, specifically versions up to and including 8.5. The flaw allows an unauthenticated attacker to circumvent intended access restrictions on the web-based building automation server, thereby exposing sensitive information. The vulnerability is remotely exploitable over the network without requiring any authentication or user interaction, as indicated by the CVSS 4.0 vector AV:N/AC:L/AT:N/UI:N/PR:N. The impact is primarily on confidentiality, with a high impact on the confidentiality metric (VC:H), while integrity and availability impacts are not indicated. The vulnerability affects critical building management functions, potentially exposing operational data or control interfaces that could be leveraged for further attacks or espionage. Although no public exploits are currently known, the critical severity score of 9.2 reflects the ease of exploitation and the sensitive nature of the affected systems. The vulnerability was reserved in May 2024 and published in November 2025, with no patches currently linked, indicating a potential window of exposure. Given the widespread use of WebCTRL and Carrier i-Vu in commercial and industrial buildings, this vulnerability represents a significant risk to facility security and operational continuity.

For European organizations, the impact of CVE-2024-5539 is substantial due to the widespread deployment of Automated Logic's WebCTRL and Carrier i-Vu systems in commercial buildings, data centers, and critical infrastructure facilities. Unauthorized access to building automation systems can lead to exposure of sensitive operational data, including HVAC controls, energy management, and security system statuses. This information leakage could facilitate further targeted attacks, including physical security breaches or disruption of building operations. Confidentiality breaches may also result in compliance violations under GDPR if personal or sensitive data is indirectly exposed. Additionally, attackers gaining insight into building operations could manipulate environmental controls, potentially causing safety hazards or operational downtime. The lack of authentication requirements for exploitation increases the risk of remote attacks from external threat actors. European organizations in sectors such as finance, healthcare, manufacturing, and government facilities are particularly vulnerable due to their reliance on secure building management systems. The potential for cascading effects on critical infrastructure elevates the threat level, making timely mitigation essential.

1. Immediate network segmentation: Isolate building automation systems from general corporate networks and the internet to reduce exposure. 2. Implement strict firewall rules to restrict access to WebCTRL and Carrier i-Vu interfaces only to authorized personnel and trusted IP addresses. 3. Deploy VPNs or secure tunnels for remote access to building automation systems to enforce authentication and encryption. 4. Monitor network traffic and system logs for unusual access patterns or unauthorized attempts to reach the building automation servers. 5. Apply principle of least privilege on user accounts and services interacting with these systems. 6. Engage with Automated Logic and Carrier for official patches or security updates as soon as they become available. 7. Conduct regular security assessments and penetration tests focusing on building management systems. 8. Develop and test incident response plans specifically addressing building automation system compromises. 9. Educate facility management and IT teams about the risks and signs of exploitation related to this vulnerability. 10. Consider deploying web application firewalls (WAF) with custom rules to detect and block unauthorized access attempts targeting this vulnerability.