9.1

CVE-2026-8066: hitachi energy rtu500 series cmu firmware Relative Path Traversal

CVSS: 9.1v3.1CriticalAwaiting analysis
Published 29-09-2026Last modified 29-09-2026
Open JSON

Vulnerability summary

CVE-2026-8066 is a critical (CVSS 9.1) Relative Path Traversal vulnerability in hitachi energy rtu500 series cmu firmware. EPSS estimates a 0.74% chance of exploitation in the next 30 days, higher than 53.9% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.74%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 29-09-2026
    PublishedVulnerability first disclosed.
  2. 29-09-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.74%

Chance of exploitation in the next 30 days

Percentile

54%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

29-09-202621-10-2026
EPSS score
0.74%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Hitachi energy1 product

1 vendor · 1 product

References

1 links