---
title: "CVE-2026-8066: Hitachi Energy RTU500 - Directory Traversal"
description: "Hitachi Energy RTU500 contains a directory traversal vulnerability in the file upload functionality, letting unauthenticated attackers write or overwrite arbitrary files on the device file system, exploit requires no authentication."
url: https://panop.io/threat-heartbeat/CVE-2026-8066/
---

# CVE-2026-8066 Hitachi Energy RTU500 - Directory Traversal

Hitachi Energy RTU500 contains a directory traversal vulnerability in the file upload functionality, letting unauthenticated attackers write or overwrite arbitrary files on the device file system, exploit requires no authentication.

CVSS base score 9.1 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.74% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-8066)

## Details

Type

Directory Traversal

Impact

File System Write, Data Tampering, Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Published

29 September 2026

Updated

15 October 2026

Weakness

[CWE-23](https://cwe.mitre.org/data/definitions/23.html)

## Vendor fix

Update to the latest version with the vulnerability fixed.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-8066](https://nvd.nist.gov/vuln/detail/CVE-2026-8066)
- [https://publisher.hitachienergy.com/preview?DocumentID=8DBD000251&LanguageCode=en&DocumentPartId=&Action=Launch](https://publisher.hitachienergy.com/preview?DocumentID=8DBD000251&LanguageCode=en&DocumentPartId=&Action=Launch)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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