---
id: CVE-2026-8065
title: >-
  An authentication bypass vulnerability in the firmware update endpoint of
  Hitachi Energy RTU500 allows an unauthenticated attacker to upload arbitrary
  firmware through a crafted POST request
summary: >-
  An authentication bypass vulnerability in the firmware update endpoint of
  Hitachi Energy RTU500 allows an unauthenticated attacker to upload arbitrary
  firmware through a crafted POST request. Successful exploitation could allow
  the attac…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'
cwe:
  - CWE-306
vendor: Hitachi Energy
product: RTU500 series CMU firmware
affected:
  - rtu500_series_cmu_firmware >= 9.0 < 12.0
published: '2026-09-29'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T10:17:13.110'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-8065'
references:
  - url: >-
      https://publisher.hitachienergy.com/preview?DocumentID=8DBD000251&LanguageCode=en&DocumentPartId=&Action=Launch
    label: cybersecurity@hitachienergy.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-29T09:30:49.084Z'
---

## Overview

An authentication bypass vulnerability in the firmware update endpoint of Hitachi Energy RTU500 allows an unauthenticated attacker to upload arbitrary firmware through a crafted POST request. Successful exploitation could allow the attacker to modify device functionality or compromise the integrity or availability of the device.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.