Hitachi Energy e-mesh EMS Vulnerability (CVE-2026-42945)

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 Background - Critical Infrastructure Sectors: Energy - Countries/Areas Deployed: Worldwide - Company Headquarters Location: Switzerland Vulnerabilities CVE-2026-42945 NGINX Plus and NGINX Open Source used in e-mesh EMS have a vulnerability in the ngx_http_rewrite_module module. The issue is tracked as CVE-2026-42945. Affected Products Hitachi Energy e-mesh EMS Hitachi Energy e-mesh EMS versions 4.1.6, e-mesh EMS versions 4.4.2, e-mesh EMS versions 4.7.0 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.

The Vulnerability

e-mesh EMS versions using NGINX v1.30.0 and below are affected.

Further details indicate that 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.

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.

Technical Details

CVEs:

• CVE-2026-42945

From a technical standpoint, the vulnerability presents several concerns:

Hitachi Energy e-mesh EMS 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.

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.

Risk & Exposure

Hitachi Energy e-mesh EMS Summary Hitachi Energy is aware of a buffer overflow vulnerability that affects e-mesh EMS product versions listed in this document. e-mesh EMS versions using NGINX v1.30.0 and below are affected. 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.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

Patching & Remediation

1. Please refer to the Recommended Immediate Actions for information about the mitigation/remediation.

2. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

3. 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.

4. General Mitigation Factors Recommended security practices and firewall configurations can help protect a process control network from attacks that originate from outside the network.

5. Recommended Practices CISA recommends users take defensive measures to minimize the exploitation risk of these vulnerabilities.

6. 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.

Analysis

This disclosure adds to a growing pattern of significant vulnerabilities affecting enterprise infrastructure.

Sources

1. https://www.cisa.gov/topics/critical-infrastructure-security-and-resilience
2. https://www.cisa.gov/topics/emergency-communications
3. https://www.cisa.gov/news-events/ics-advisories/icsa-26-188-03
4. https://www.hitachienergy.com/contact-us/
5. https://www.cisa.gov/notification
6. https://www.cisa.gov/privacy-policy
7. https://nvd.nist.gov/vuln/detail/CVE-2026-42945
8. https://ubuntu.com/security/cve-2026-42945