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Fencer Vulns
critical 9.1

CVE-2026-8065 json

An authentication bypass vulnerability in the firmware update endpoint of Hitachi Energy RTU500 end-of-life versions allows an unauthentica…

published 2026-09-29 40 d ago modified 2026-09-29 40 d ago also EUVD-2026-88666

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

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

0.49% chance of exploitation in the next 30 days, higher than 42% 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-306 Missing Authentication for Critical Functionality

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.