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Fencer Vulns
critical 9.1

CVE-2026-8066 json

A directory traversal vulnerability in the file upload functionality of Hitachi Energy RTU500 end-of-life versions allows an unauthenticate…

published 2026-09-29 41 d ago modified 2026-09-29 40 d ago also EUVD-2026-88669

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 54%
public exploits
0
none known

Summary

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.

Patch / fix

  • Hitachi Energy RTU500 series CMU firmware 12.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-26-279-06 updated cvss 9.1

Hitachi Energy RTU500

  • Hitachi Energy RTU500 series CMU Firmware vers:RTU500_series_CMU_Firmware/<=11.x
    affected: fixed in 12.7.8

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
40 d ago

Exploit prediction

0.74% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Affected products

  • Hitachi Energy RTU500 series CMU firmware

Classification

Weakness
  • CWE-23 Relative Path Traversal

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.