The vulnerability identified as CVE-2026-25872 affects the JUNG Smart Panel 5.1 KNX firmware versions L1.12.22 and prior. It is classified as a CWE-22 path traversal flaw, where the embedded web interface fails to properly sanitize or restrict file path inputs. This allows an unauthenticated remote attacker to craft specially designed requests that traverse directories on the device's filesystem, bypassing intended access controls. As a result, attackers can read arbitrary files, including sensitive configuration files that may contain credentials, network settings, or other critical information. The vulnerability does not require any authentication or user interaction, making it easier to exploit remotely. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and impacts confidentiality only (VC:L), with no impact on integrity or availability. Although no public exploits have been reported yet, the nature of the vulnerability and the widespread deployment of JUNG Smart Panels in building automation systems pose a significant risk. Attackers could leverage disclosed information for further attacks or lateral movement within a network. The lack of a patch at the time of reporting necessitates immediate compensating controls to reduce exposure. Given the device's role in smart building management, confidentiality breaches could lead to privacy violations or facilitate sabotage of building systems.

For European organizations, particularly those managing smart buildings, commercial facilities, or critical infrastructure using JUNG Smart Panel 5.1 KNX devices, this vulnerability presents a moderate confidentiality risk. Unauthorized disclosure of configuration files could expose network credentials, device settings, or integration details with other building management systems. This information could be used by attackers to escalate privileges, conduct further reconnaissance, or disrupt building operations indirectly. Since the vulnerability is exploitable without authentication, attackers can target exposed devices over the network, increasing the attack surface. The impact is heightened in sectors such as energy management, healthcare facilities, and government buildings where building automation security is critical. Additionally, the exposure of sensitive data may lead to regulatory compliance issues under GDPR if personal or operational data is compromised. While the vulnerability does not directly affect system integrity or availability, the potential for information leakage and subsequent attacks makes it a significant concern for European organizations relying on these devices.

1. Immediately restrict network access to JUNG Smart Panel devices by implementing network segmentation and firewall rules that limit access to trusted management networks only. 2. Monitor network traffic to and from the devices for unusual or unauthorized access attempts, especially HTTP requests containing suspicious path traversal patterns (e.g., '../'). 3. Disable or restrict the embedded web interface if not required or replace it with a more secure management method. 4. Engage with ALBRECHT JUNG GMBH & CO. KG to obtain firmware updates or patches addressing this vulnerability as soon as they become available. 5. Implement strong authentication and access control measures on the management network to reduce exposure. 6. Conduct regular security audits and vulnerability assessments on building automation systems to identify and remediate similar issues proactively. 7. Educate facility management and IT teams about the risks and indicators of compromise related to this vulnerability. 8. If possible, deploy intrusion detection systems capable of detecting path traversal attack signatures targeting these devices.