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Hitachi Energy reports vulnerabilities in RTU500 series

Source Decision Insights Threat Desk Published September 16, 2025 Companies 1
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56th article in the last 90 days, one of 130 articles referencing Cybersecurity and Infrastructure Security Agency (CISA). Previous coverage: CISA issues eight advisories on Industrial Control Systems (Sep 2025).

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1. EXECUTIVE SUMMARY

  • Common Vulnerability Scoring System (CVSS) v4 8.2
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Hitachi Energy
  • Equipment: RTU500 series
  • Vulnerabilities: NULL Pointer Dereference, Improper Validation of Integrity Check Value, Improper Restriction of XML External Entity Reference, Heap-based Buffer Overflow, Integer Overflow or Wraparound, Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion'), Stack-based Buffer Overflow

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could cause a Denial of Service (DoS) condition in RTU500 devices.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Hitachi Energy reports that the following products are affected:

  • Hitachi Energy RTU500 series: Version 13.6.1 (CVE-2023-2953, CVE-2025-39203, CVE-2025-6021)
  • Hitachi Energy RTU500 series: Versions 12.7.1 through 12.7.7 (CVE-2023-2953, CVE-2025-39203, CVE-2025-6021)
  • Hitachi Energy RTU500 series: Versions 13.4.1 through 13.4.4 (CVE-2025-39203)
  • Hitachi Energy RTU500 series: Versions 13.5.1 through 13.5.3 (CVE-2023-2953, CVE-2025-39203, CVE-2025-6021)
  • Hitachi Energy RTU500 series: Versions 13.7.1 through 13.7.6

3.2 VULNERABILITY OVERVIEW

3.2.1 NULL POINTER DEREFERENCE CWE-476

A vulnerability has been identified in the openLDAP library used in Central Account Management (CAM) client. This issue can lead to a DoS condition when a specially crafted request may cause a null pointer to dereference, resulting in affected CMU to automatically recovering itself by rebooting.

CVE-2023-2953 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

A CVSS v4 score has also been calculated for CVE-2023-2953. A base score of 8.2 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.2.2 IMPROPER VALIDATION OF INTEGRITY CHECK VALUE CWE-354

A vulnerability exists in the Indirect Evaporative Cooling (IEC) 61850 protocol of the RTU500 product series. An IEC 61850-8 crafted message content from a device (e.g. an IED) or remote system can cause a DoS resulting in disconnection of the device to the RTU 500 until next reboot.

CVE-2025-39203 has been assigned to this vulnerability. A CVSS v3.1 base score of 4.3 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L).

A CVSS v4 score has also been calculated for CVE-2025-39203. A base score of 5.3 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N).

3.2.3 IMPROPER RESTRICTION OF XML EXTERNAL ENTITY REFERENCE CWE-611

A vulnerability has been identified in the libexpat library used in IEC 61850 client and server components of the RTU500 product series. An authenticated and authorized malicious user could load a crafted XML input which may lead to memory mismanagement potentially causing RTU500 to reboot.

CVE-2024-45490 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

A CVSS v4 score has also been calculated for CVE-2024-45490. A base score of 7.1 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.2.4 HEAP-BASED BUFFER OVERFLOW CWE-122

A vulnerability has been identified in libexpat library used in the IEC 61850 client and server components of the RTU500 product series. An authenticated and authorized malicious user could load a crafted XML input which may lead to heap corruption potentially causing RTU500 to reboot.

CVE-2024-45491 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

A CVSS v4 score has also been calculated for CVE-2024-45491. A base score of 7.1 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.2.5 INTEGER OVERFLOW OR WRAPAROUND CWE-190

A vulnerability has been identified in libexpat library used in the IEC 61850 client and server components of the RTU500 product series. An authenticated and authorized malicious user could load a crafted XML input which leads to an integer overflow potentially causing RTU500 to reboot.

CVE-2024-45492 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

A CVSS v4 score has also been calculated for CVE-2024-45492. A base score of 7.1 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.2.6 IMPROPER RESTRICTION OF RECURSIVE ENTITY REFERENCES IN DTDS ('XML ENTITY EXPANSION') CWE-776

A vulnerability has been identified in libexpat library used in the IEC 61850 client and server components of the RTU500 product series. An authenticated and authorized malicious user could load a crafted XML input which may lead to a memory mismanagement potentially causing RTU500 to reboot.

CVE-2024-28757 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

A CVSS v4 score has also been calculated for CVE-2024-28757. A base score of 7.1 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.2.7 STACK-BASED BUFFER OVERFLOW CWE-121

A vulnerability exists in libxml library used by RTU500 Web server functionality. An authenticated and authorized malicious user could send a crafted XML message which may lead to buffer overflow potentially causing RTU500 to reboot.

CVE-2025-6021 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

A CVSS v4 score has also been calculated for CVE-2025-6021. A base score of 6.9 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Energy
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Switzerland

3.4 RESEARCHER

Hitachi Energy reported these vulnerabilities to CISA.

4. MITIGATIONS

Hitachi Energy has identified the following specific workarounds and mitigations users can apply to reduce risk:

  • (CVE-2023-2953, CVE-2025-39203, CVE-2025-6021) RTU500 series CMU Firmware version 12.7.1 – 12.7.7: Update to CMU Firmware version 12.7.8 when available
  • (CVE-2023-2953, CVE-2025-39203, CVE-2025-6021) RTU500 series CMU Firmware version 13.5.1 – 13.5.3: Update to CMU Firmware version 13.5.4
  • (CVE-2023-2953, CVE-2025-39203, CVE-2025-6021) RTU500 series CMU Firmware version 13.6.1: Update to CMU Firmware version 13.6.3
  • (CVE-2023-2953) RTU500 series CMU Firmware version 12.7.1 – 12.7.7: Follow general mitigation factors /workarounds
  • (CVE-2023-2953, CVE-2025-39203) RTU500 series CMU Firmware version 13.6.1, RTU500 series CMU Firmware version 13.5.1 – 13.5.3, RTU500 series CMU Firmware version 13.7.1 – 13.7.6: Follow general mitigation factors/workarounds.
  • (CVE-2023-2953, CVE-2024-45490, CVE-2024-45491, CVE-2024-45492, CVE-2024-28757, CVE-2025-6021) RTU500 series CMU Firmware version 13.7.1 – 13.7.6: Update to CMU Firmware version 13.7.7
  • (CVE-2025-39203) RTU500 series CMU Firmware version 12.7.1 – 12.7.7: Follow general mitigation factors/ workarounds.
  • (CVE-2025-39203) RTU500 series CMU Firmware version 13.4.1 – 13.4.4, RTU500 series CMU Firmware version 13.7.1 – 13.7.6: Update to CMU Firmware version 13.7.7
  • (CVE-2025-39203) RTU500 series CMU Firmware version 13.4.1 – 13.4.4: Follow General Mitigation Factors/Workarounds.
  • (CVE-2024-45490, CVE-2024-45491, CVE-2024-45492, CVE-2024-28757) RTU500 series CMU Firmware version 13.7.1 – 13.7.6: Follow general mitigation factors/workarounds.
  • (CVE-2025-6021) RTU500 series CMU Firmware version 13.6.1, RTU500 series CMU Firmware version 12.7.1 – 12.7.7, RTU500 series CMU Firmware version 13.5.1 – 13.5.3, RTU500 series CMU Firmware version 13.7.1 – 13.7.6: Follow general mitigation factors/workarounds.

For more information see the associated Hitachi Energy PSIRT security advisory 8DBD000220 Multiple Vulnerabilities in Hitachi Energy's RTU500 series Product.

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, such as:

  • 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). Recognize VPNs may have vulnerabilities, should be updated to the most recent version available, and are 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 Industrial Control Systems (ICS) webpage on cisa.gov. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving ICS 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.

CISA also recommends users take the following measures to protect themselves from social engineering attacks:

No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

  • September 16, 2025: Initial Republication of Hitachi Energy PSIRT 8DBD000220

Blog post, originally published by CISA at cisa.gov.

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