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CVE-2021-35534 Hitachi Energy CVE debrief

CVE-2021-35534 is an industrial-control vulnerability in Hitachi Energy Relion 670/650/SAM600-IO products. CISA and the vendor describe a database-schema weakness that can be abused after an attacker already has valid account credentials or a session ticket. Through the configuration tool using the proprietary ODBC protocol on TCP 2102, an attacker may manipulate database tables for privilege escalation, leading to unauthorized modification or permanent device disabling. The issue was publicly disclosed on 2021-11-04 and later updated in the advisory record, with the latest source revision dated 2025-02-25.

Vendor
Hitachi Energy
Product
Relion 670 series
CVSS
HIGH 7.2
CISA KEV
Not listed in stored evidence
Original CVE published
2021-12-09
Original CVE updated
2021-12-09
Advisory published
2021-12-09
Advisory updated
2021-12-09

Who should care

OT and ICS operators using Hitachi Energy Relion 670 or 650 series, SAM600-IO deployments, and teams responsible for protection relays, substation automation, and configuration management should prioritize this advisory. Security teams should also care if any maintenance workflow exposes the configuration tool or TCP 2102 to broader-than-necessary access.

Technical summary

The advisory says the flaw is in the product’s internal database schema. Exploitation requires prior access to valid credentials for any account or a session ticket for an account. Once authenticated, an attacker can use the configuration tool over proprietary ODBC on TCP 2102 to manipulate database tables and escalate privileges. The reported impact is unauthorized modification or permanent disabling of the device. The advisory includes vendor fixes for multiple product/version branches, including Relion 670 series, Relion 650 series, and Relion SAM600-IO.

Defensive priority

High. The vulnerability affects operational technology devices and can result in device disablement or unauthorized changes, but it requires valid account access first. That makes access control hardening and timely patching the immediate priorities.

Recommended defensive actions

  • Update affected systems to the vendor-fixed versions listed in the advisory, including Relion 670/650/SAM600-IO 2.2.1.8, Relion 670 2.2.2.5, Relion 670 2.2.3.5, Relion 670/650 2.2.4.3, Relion 670/650/SAM600-IO 2.2.5.2, 2
  • Confirm which exact product family and revision is deployed before scheduling remediation, since affected and fixed versions vary by branch.
  • Restrict and monitor access to the configuration tool and the TCP 2102 ODBC service so only authorized maintenance systems and users can reach it.
  • Protect account credentials and session tickets with strong access control, least privilege, and secure handling of remote or shared maintenance workflows.
  • Use CISA’s industrial-control security guidance and defense-in-depth practices to segment OT assets and limit management-plane exposure.
  • Validate that no unauthorized configuration changes or unexpected device disablement events have occurred on exposed relays and related systems.

Evidence notes

All substantive claims are taken from the supplied CISA CSAF advisory content and the referenced vendor/CISA links. The advisory states that exploitation requires prior credential or session-ticket access and that the configuration tool uses proprietary ODBC over TCP 2102. The supplied source also lists affected product families, version-specific remediations, and no KEV designation.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-35534 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-35534

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-35534 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-35534

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2025/icsa-25-065-02.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-065-02

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/uscert/ics/alerts/ICS-ALERT-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/topics/industrial-control-systems

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://us-cert.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/publications/Cybersecurity_Best_Practices_for_Industrial_Control_Systems.pdf

    Reference

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.