CVE-2026-8066

criticalpriority · track · 0EPSS 0.007 · 54 %ileDEUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
0.74% (54th) EPSS
CVSS 9.1 · critical
Is it mine?
6 products
Check your exposure
Who says so?
2 sources
cert_bund · cisa_csaf_ot

EPSS · scored 2026-10-22

A directory traversal vulnerability in the file upload functionality of Hitachi Energy RTU500 end-of-life versions allows an unauthenticated attacker to write or overwrite arbitrary files on the device file system. Depending on the files affected, successful exploitation could result in unauthorized modification of device data or disruption of the device’s intended operation.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedRTU500 series CMU Firmwarecisa_csaf_ot

    Upgrade to version 12.7.8 or 13.9.1 or latest

02

cvss

Technical severity, 0–10. One row per scoring source.

9.1
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.3–9.1

v3.19.1criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Hsecondary · CISA US
v3.19.1criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Hsecondary · cybersecurity@hitachienergy.comexploitability 3.9 · impact 5.2
v3.18.3highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

05

affected products (6)

Products and version ranges known to be affected.

06

advisories (2)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-3658Hitachi Energy RTU500: Mehrere SchwachstellenDeutsch2026-09-29csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Hitachi Energy RTU500 ausnutzen, um beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, die Gerätefunktionalität zu verändern oder Denial-of-Service-Zustände zu verursachen.

  • ICSA-26-279-06Hitachi Energy RTU5002026-09-29icsa · cisa_csaf_otUS

    Hitachi Energy is publishing this cybersecurity advisory in response to the security findings reported by Dragos affecting end-of-life RTU500 CMU firmware version 9.x. The reported findings are associated with legacy RTU500 firmware versions that were developed according to the cybersecurity requirements, threat landscape, and industry practices that existed at the time of their release. As cybersecurity threats and security expectations have evolved, these end-of-life versions no longer incorporate many of the security controls and hardening measures that are standard in modern industrial control systems. Over successive RTU500 releases, Hitachi Energy has continuously enhanced the security of the product through the introduction of additional security features, protocol hardening, stronger authentication and access controls, encrypted communications, and other security-by-design improvements. While the findings reported by Dragos do not affect currently supported RTU500 CMU firmware versions, there is a likelihood that the end-of-life versions 11.x and prior are affected by these vulnerabilities. Since the end-of-life versions are no longer maintained with security updates, Hitachi Energy strongly recommends upgrading to a currently supported RTU500 firmware version. Customers should also implement appropriate defense-in-depth measures and cybersecurity best practices to reduce risk and strengthen the security posture of their operational environments. Please refer to the Recommended Immediate Actions for information about the mitigation/remediation.

07

sources

Which sources assert this record, and when.

published 2026-09-29modified 2026-09-29
08

references (1) nvd

External citations — patches, advisories, analysis.

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