View CSAF Summary Successful exploitation of this vulnerability could allow an attacker to take control of the victim's browser. The following versions of Kieback & Peter DDC Building Controllers are affected: DDC4002 DDC4100 DDC4200 DDC4200-L DDC4400 DDC4002e DDC4200e DDC4400e DDC4020e DDC4040e DDC520 CVSS Vendor Equipment Vulnerabilities v3 5.3 Kieback & Peter Kieback & Peter DDC Building Controllers Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') Background Critical Infrastructure Sectors: Commercial Facilities, Communications, Financial Services, Food and Agriculture, Government Services and Facilities, Healthcare and Public Health, Information Technology Countries/Areas Deployed: Austria, China, France, Germany, United Arab Emirates Company Headquarters Location: Germany Vulnerabilities Expand All + CVE-2026-4293 The affected products are vulnerable to cross-site scripting (XSS), enabling JavaScript to be executed by the victim's browser, which allows the attacker to control the browser. View CVE Details Affected Products Kieback & Peter DDC Building Controllers Vendor: Kieback & Peter Product Version: Kieback & Peter DDC4002: Product Status: known_affected Remediations Mitigation Kieback & Peter DDC Building Controllers are developed and designed for use in closed building automation networks. The system is protected by a multi-level perimeter against attacks, especially from outside, by dividing it into operational technology (OT) zones with firewalls. Building automation systems (BA systems) in general should not be directly accessible from untrusted networks, especially from the Internet, but should be protected by consistently applying the defense-in-depth strategy. This concept is supported by organizational measures in the building as part of a safety management system. In order to achieve safety, measures are required at all levels. Vendor fix The DDC4002, DDC4100, DDC4200, DDC4200-L and DDC4400 controllers are end-of-maintenance, therefore the recommendations for these devices are as follows: These devices must be operated in a strictly separate OT environment. Vendor fix The DDC4002, DDC4100, DDC4200, DDC4200-L and DDC4400 controllers are end-of-maintenance, therefore the recommendations for these devices are as follows: Only trusted individuals should be granted network access to the DDC web portal. Vendor fix The DDC4002, DDC4100, DDC4200, DDC4200-L and DDC4400 controllers are end-of-maintenance, therefore the recommendations for these devices are as follows: Access to the web portal should be disabled in the device configuration if not required. Vendor fix The DDC4002, DDC4100, DDC4200, DDC4200-L and DDC4400 controllers are end-of-maintenance, therefore the recommendations for these devices are as follows: Users should be informed that only links from trusted sources should be used to access the web service. Vendor fix For the DDC520, DDC4002e, DDC4200e, DDC4400e, DDC4020e, and DDC4040e controllers, Kieback & Peter recommends the following safety measure: Restrict network access to the device Vendor fix For the DDC520, DDC4002e, DDC4200e, DDC4400e, DDC4020e, and DDC4040e controllers, Kieback & Peter recommends the following safety measure: Do not directly connect the device to the Internet Vendor fix Update the firmware to the latest available version: DDC4002e -> Update to version 1.23.5 or newer Vendor fix Update the firmware to the latest available version: DDC4200e -> Update to version 1.23.5 or newer Vendor fix Update the firmware to the latest available version: DDC4400e -> Update to version 1.23.5 or newer Vendor fix Update the firmware to the latest available version: DDC4020e -> Update to version 1.23.5 or newer Vendor fix Update the firmware to the latest available version: DDC4040e -> Update to version 1.23.5 or newer Vendor fix Update the firmware to the latest available version: DDC520 -> Update to version 1.24.2 or newer Relevant CWE: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') Metrics CVSS Version Base Score Base Severity Vector String 3.1 5.3 MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Acknowledgments Maximilian Hildebrand of G DATA Advanced Analytics reported this vulnerability to CISA Legal Notice and Terms of Use This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy). Recommended Practices CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet. Locate control system networks and remote devices behind firewalls and isolating them from business networks. When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices. CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures. CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies. CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies. Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents. CISA also recommends users take the following measures to protect themselves from social engineering attacks: Do not click web links or open attachments in unsolicited email messages. Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams. Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks. No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time. Revision History Initial Release Date: 2026-05-19 Date Revision Summary 2026-05-19 1 Initial Publication Legal Notice and Terms of Use

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