Medium Patch available
Hitachi Energy warns of flaws in RTU500 CMU firmware
CISA ICS AdvisoriesHitachi Energy, RTU500 · energyCVE-2026-17539, CVE-2026-28388, CVE-2026-6732
What happened. Hitachi Energy reported vulnerabilities in RTU500 series CMU firmware across several listed version ranges. If exploited, they could affect confidentiality, integrity and availability of the product. The report refers readers to the vendor's recommended actions.
Who is affected. Hitachi Energy RTU500 series CMU firmware in ranges 12.7.1–12.7.7, 13.5.1–13.5.4, 13.6.1–13.6.3, 13.7.1–13.7.8 and 13.8.1–13.8.2. Energy sector.
What to do. Check whether you run RTU500 CMU firmware in the listed ranges, then follow Hitachi Energy's recommended immediate actions for mitigation or remediation.
Editor's reading
Forasset ownerOT security lead
- Purdue level
- L1
Why: The RTU500 is a remote terminal unit, which sits at the controller level (L1).
- Are you exposed?
Check the asset inventory for RTU500 CMU firmware versions within the ranges listed in the advisory.
Inferred from the facts above, not stated by the source. Check it against your own site before acting.
Source: CISA ICS Advisories (opens cisa.gov)
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