CVE-2021-35535
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedInsecure Boot Image vulnerability in Hitachi Energy Relion Relion 670/650/SAM600-IO series allows an attacker who manages to get access to the front network port and to cause a reboot sequences of the device may exploit the vulnerability, where there is a tiny time gap during the booting process where an older version of VxWorks is loaded prior to application firmware booting, could exploit the vulnerability in the older version of VxWorks and cause a denial-of-service on the product. This issue affects: Hitachi Energy Relion 670 Series 2.2.2 all revisions; 2.2.3 versions prior to 2.2.3.3. Hitachi Energy Relion 670/650 Series 2.2.0 all revisions; 2.2.4 all revisions. Hitachi Energy Relion 670/650/SAM600-IO 2.2.1 all revisions.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceInsecure Boot Image vulnerability in Hitachi Energy Relion devices allows an attacker with front network port access to trigger a reboot and exploit a time gap during boot where an older vulnerable version of VxWorks loads prior to the application firmware, causing denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 2.2.3, <= 2.2.3.3= 2.2.0= 2.2.1= 2.2.2= 2.2.4= 2.2.0= 2.2.1= 2.2.4= 2.2.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify the Relion device modelCheck the device nameplate, web interface, or management interface for the exact model (Relion 670, 650, or Sam600 Io)Affected if Device is a Relion 670, 650, or Sam600 Io model
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Determine the installed firmware versionAccess the device management interface, web UI, or use vendor-provided diagnostic tools to retrieve the current firmware versionAffected if Firmware version cannot be determined or retrieved
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Compare firmware version against affected ranges for Relion 670Check if version is: >= 2.2.3 AND <= 2.2.3.3, OR equals 2.2.0, 2.2.1, 2.2.2, or 2.2.4Affected if Version matches any of these: 2.2.0, 2.2.1, 2.2.2, 2.2.3 through 2.2.3.3, or 2.2.4
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Compare firmware version against affected ranges for Relion 650Check if version equals 2.2.0, 2.2.1, or 2.2.4Affected if Version equals 2.2.0, 2.2.1, or 2.2.4 on a Relion 650 device
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Compare firmware version against affected ranges for Relion Sam600 IoCheck if version equals 2.2.1Affected if Version equals 2.2.1 on a Relion Sam600 Io device
The device is affected if it is a Relion 670, 650, or Sam600 Io running any of the specific firmware versions listed in the affected ranges.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply vendor-provided firmware updates (2.2.3.3 or later for affected 2.2.3 versions; contact Hitachi Energy for patched versions for other affected releases) and restrict physical/network access to device management ports.
- Consultation6.0 h
- Implementation8.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-35535 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-35535 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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