CVE-2021-35535

Service interruption via older VxWorks boot image

Published Nov 18, 2021 · Updated Sep 16, 2024

Insecure boot image handling in Hitachi Energy Relion 670 series 2.2.2 and 2.2.3 before 2.2.3.3 allows attackers to interrupt service via reboot. During startup, the boot chain temporarily loads an older VxWorks image before the application firmware, exposing vulnerabilities in that image. Exploitation requires access to the front network port and control of a reboot sequence; successful exploitation stops device service.

CVSS severity8.1
High
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure boot image handling in Hitachi Energy Relion 670 series 2.2.2 and 2.2.3 before 2.2.3.3 allows attackers to interrupt service via reboot. During startup, the boot chain temporarily loads an older VxWorks image before the application firmware, exposing vulnerabilities in that image. Exploitation requires access to the front network port and control of a reboot sequence; successful exploitation stops device service.

The record

CVE
CVE-2021-35535
Published
Nov 18, 2021
Updated
Sep 16, 2024
Vendor
Hitachi Energy
Product
Relion 670 series
Classifications
CWE-1188, T0814
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.2.2 all revisions
  2. Affected versionversion=2.2.3 <2.2.3.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Hitachi Energy · Relion 670 seriesversion=2.2.2 all revisions; version=2.2.3 <2.2.3.3

Published CVSS scores

8.1Hitachi EnergyCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1188Insecure Default Initialization of Resource
T0814Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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