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Critical severity · published Sep 29, 2026
CVE-2026-8065
An authentication bypass vulnerability in the firmware update endpoint of Hitachi Energy RTU500 end-of-life versions allows an unauthenticated attacker to upload arbitrary…
9.1
CVSS
0.5%
EPSS
No
On KEV
Description
An authentication bypass vulnerability in the firmware update endpoint of Hitachi Energy RTU500 end-of-life versions 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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 42% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RS
RTU500 series CMU firmware · Hitachi Energy
9.0 before 12.0 · source: vendor
Affected product
RS
RTU500 series CMU firmware
Hitachi Energy
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-8065
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-8065
publisher.hitachienergy.com
https://publisher.hitachienergy.com/preview?DocumentID=8DBD000251&LanguageCode=en&DocumentPartId=&Action=Launch
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