Original Article Summary

View CSAF Summary Hitachi Energy is aware of a buffer overflow vulnerability that affects e-mesh EMS product versions listed in this document. Successful exploitation of this vulnerability could lead to a buffer overflow condition, potentially resulting in application outages (denial of service) and possible arbitrary code execution. Please refer to the Recommended Immediate Actions for information about the mitigation/remediation. The following versions of Hitachi Energy e-mesh EMS are affected: Hitachi Energy e-mesh EMS 4.1.6, 4.4.2, 4.7.0 CVSS Vendor Equipment Vulnerabilities v3 8.1 Hitachi Energy Hitachi Energy e-mesh EMS Heap-based Buffer Overflow Background Critical Infrastructure Sectors: Energy Countries/Areas Deployed: Worldwide Company Headquarters Location: Switzerland Vulnerabilities Expand All + CVE-2026-42945 NGINX Plus and NGINX Open Source used in e-mesh EMS have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when the rewrite directive is followed by a rewrite, if, or set directive and an unnamed Perl-Compatible Regular Expression (PCRE) capture (for example, $1, $2) with a replacement string that includes a question mark (?). An unauthenticated attacker along with conditions beyond its control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. e-mesh EMS versions using NGINX v1.30.0 and below are affected. View CVE Details Affected Products Hitachi Energy e-mesh EMS Vendor: Hitachi Energy Product Version: e-mesh EMS versions 4.1.6, e-mesh EMS versions 4.4.2, e-mesh EMS versions 4.7.0 Product Status: known_affected Remediations Vendor fix Apply hotfix for respective e-mesh EMS versions to update NGINX to either v1.30.2 or latest Mitigation Ensure rewrite configuration does not contain "?" to replace unnamed captures, and ensure ASLR is set to active (value=2) across all deployment targets covering all 3 versions. Mitigation Underlying Ubuntu Server 20.04 LTS is End of Life. For e-mesh EMS versions 4.1.6/4.4.2 using Ubuntu 20.04 LTS, upgrade to Ubuntu Server 22.04, or 24.04, or activate Ubuntu Pro/ESM as an interim measure. Relevant CWE: CWE-122 Heap-based Buffer Overflow Metrics CVSS Version Base Score Base Severity Vector String 3.1 8.1 HIGH CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H 4.0 9.2 CRITICAL CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Acknowledgments Hitachi Energy Internal Team 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. Additional information on Industrial Control Systems Cybersecurity Best Practices can be found in the Hitachi Energy “Industrial Control Systems Cybersecurity Best Practices” Cybersecurity Notification. [1] SSVC SSVCv2/E:N/A:N/2026-06-29T17:00:59Z/ 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 these vulnerabilities. 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 8DBD000253 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: 2026-06-30 Date Revision Summary 2026-06-30 1 Initial public release 2026-07-07 2 Initial CISA Republication of Hitachi Energy PSIRT 8DBD000253 advisory Legal Notice and Terms of Use