Hitachi Energy Relion REB500 Product

View CSAF Summary Hitachi Energy is aware of vulnerabilities that affect the Relion REB500 product versions listed in this document. Authenticated users with certain roles can exploit the vulnerabilities to access and modify the directory contents they are not authorized to do so. Please refer to the Recommended Immediate Actions for information about the mitigation/remediation. The following versions of Hitachi Energy Relion REB500 Product are affected: Relion REB500 vers:Relion_REB500/<=8.3.3.0 (CVE-2026-2459, CVE-2026-2460) CVSS Vendor Equipment Vulnerabilities

v3 6.8 Hitachi Energy Hitachi Energy Relion REB500 Product Privilege Defined With Unsafe Actions

Background Critical Infrastructure Sectors: Energy Countries/Areas Deployed: Worldwide Company Headquarters Location: Switzerland Vulnerabilities Expand All + CVE-2026-2459 A vulnerability exists in REB500 for an authenticated user with Installer role to access and alter the contents of directories that the role is not authorized to do so. View CVE Details Affected Products Hitachi Energy Relion REB500 Product Vendor: Hitachi Energy Product Version: REB500 versions 8.3.3.0 and prior Product Status: known_affected Remediations Vendor fix Hitachi Energy recommends that users update to version 8.3.3.1. Mitigation For CVE-2026-2459, as a mitigation strategy, users may also disable the Installer role and enable it only during the firmware update process. Relevant CWE: CWE-267 Privilege Defined With Unsafe Actions Metrics CVSS Version Base Score Base Severity Vector String

3.1 6.5 MEDIUM CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

CVE-2026-2460 A vulnerability exists in REB500 for an authenticated user with low-level privileges to access and alter the content of directories by using the DAC protocol that the user is not authorized to do so. View CVE Details Affected Products Hitachi Energy Relion REB500 Product Vendor: Hitachi Energy Product Version: REB500 versions 8.3.3.0 and prior Product Status: known_affected Remediations Vendor fix Update to version 8.3.3.1 Mitigation Apply general mitigation factors Relevant CWE: CWE-267 Privilege Defined With Unsafe Actions Metrics CVSS Version Base Score Base Severity Vector String

3.1 6.8 MEDIUM CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Acknowledgments Hitachi Energy reported this vulnerability to CISA. Notice The information in this document is subject to change without notice and should not be construed as a commitment by Hitachi Energy. Hitachi Energy provides no warranty, express or implied, including warranties of merchantability and fitness for a particular purpose, for the information contained in this document, and assumes no responsibility for any errors that may appear in this document. In no event shall Hitachi Energy or any of its suppliers be liable for direct, indirect, special, incidental or consequential damages of any nature or kind arising from the use of this document, or from the use of any hardware or software described in this document, even if Hitachi Energy or its suppliers have been advised of the possibility of such damages. This document and parts hereof must not be reproduced or copied without written permission from Hitachi Energy and the contents hereof must not be imparted to a third party nor used for any unauthorized purpose. All rights to registrations and trademarks reside with their respective owners. Support For additional information and support please contact your product provider or Hitachi Energy service organization. For contact information, see https://www.hitachienergy.com/contact-us/ for Hitachi Energy contact-centers. General Mitigation Factors Recommended security practices and firewall configurations can help protect a process control network from attacks that originate from outside the network. Such practices include that process control systems are physically protected from direct access by unauthorized personnel, have no direct connections to the Internet, and are separated from other networks by means of a firewall system that has a minimal number of ports exposed, and others that have to be evaluated case by case. Process control systems should not be used for Internet surfing, instant messaging, or receiving e-mails. Portable computers and removable storage media should be carefully scanned for viruses before they are connected to a control system. Proper password policies and processes should be followed. 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 exploitation risk of this vulnerability. Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the internet. Locate control system networks and remote devices behind firewalls and isolate 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 recent version available. Also recognize VPN is only as secure as its 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. 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 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. Advisory Conversion Disclaimer This ICSA is a verbatim republication of Hitachi Energy PSIRT 8DBD000217 from a direct conversion of the vendor's Common Security Advisory Framework (CSAF) advisory. This is republished to CISA's website as a means of increasing visibility and is provided "as-is" for informational purposes only. CISA is not responsible for the editorial or technical accuracy of republished advisories and provides no warranties of any kind regarding any information contained within this advisory. Further, CISA does not endorse any commercial product or service. Please contact Hitachi Energy PSIRT directly for any questions regarding this advisory. Revision History Initial Release Date: 2026-02-24 Date Revision Summary

2026-02-24 1 Initial public release

2026-03-03 2 Initial CISA Republication of Hitachi Energy PSIRT 8DBD000217 advisory

Legal Notice and Terms of Use

Source: CISA Alerts