Hitachi Energy Relion 670/650 and SAM600-IO Series

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1. EXECUTIVE SUMMARY

• CVSS v4 8.7
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Hitachi Energy
• Equipment: Relion 670/650 and SAM600-IO
• Vulnerability: Allocation of Resources Without Limits or Throttling

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow attackers to cause a denial-of-service that disrupts critical functions in the device.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Hitachi Energy reports that the following products are affected:

• Hitachi Energy Relion 650: Version 2.2.4.4
• Hitachi Energy Relion 650: Version 2.2.5.6
• Hitachi Energy Relion 650: All versions from 2.2.6.0 to 2.2.6.2
• Hitachi Energy Relion 670: Version 2.2.2.6
• Hitachi Energy Relion 670: Version 2.2.3.7
• Hitachi Energy Relion 670: Version 2.2.4.4
• Hitachi Energy Relion 670: Version 2.2.5.6
• Hitachi Energy Relion 670: All versions from 2.2.6.0 to 2.2.6.2
• Hitachi Energy SAM600-IO: Version 2.2.5.6

3.2 VULNERABILITY OVERVIEW

3.2.1 ALLOCATION OF RESOURCES WITHOUT LIMITS OR THROTTLING CWE-770

A denial-of-service vulnerability due to improper prioritization of network traffic over protection mechanism exists in the Relion 670/650 and SAM600-IO series device that if exploited, could potentially cause critical functions like LDCM (Line Distance Communication Module) to malfunction.

CVE-2025-2403 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-2025-2403. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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 PSIRT reported this vulnerability to CISA.

4. MITIGATIONS

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

• Relion 670 series version 2.2.6 revisions up to 2.2.6.2, Relion 650 series version 2.2.6 revisions up to 2.2.6.2: Fixed in version 2.2.6.3. Update to version 2.2.6.4 (when available) or latest
• Relion 670 series version 2.2.5.6, Relion 650 series version 2.2.5.6, SAM600-IO series version 2.2.5.6: Fixed in version 2.2.5.7. Update to version 2.2.5.8 or latest
• Relion 670 series version 2.2.4.4, Relion 650 series version 2.2.4.4: Update to version 2.2.4.5 or latest
• All affected products: Apply general mitigation factors

For more information see the associated Hitachi Energy PSIRT security advisory 8DBD000216 Cybersecurity Advisory - DoS Vulnerability in Hitachi Energy Relion 670/650 and SAM600-IO series products.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, 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 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.

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

5. UPDATE HISTORY

July 1, 2025: Initial Republication of Hitachi Energy PSIRT 8DBD000216

• Hitachi Energy