CVE-2021-21565
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 · uneditedDell PowerScale OneFS versions 9.1.0.3 and earlier contain a denial of service vulnerability. SmartConnect had an error condition that may be triggered to loop, using CPU and potentially preventing other SmartConnect DNS responses.
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 · moderate confidenceDell PowerScale OneFS SmartConnect contains an error condition that can be triggered to enter an infinite loop, consuming CPU resources and preventing other SmartConnect DNS responses from being served, resulting in 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<= 9.1.0.3CVSS 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
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 PowerScale OneFS versionRun the command 'isi version' or access the OneFS web interface to view the system version under the Cluster > Overview sectionAffected if The installed version is 9.1.0.3 or lower (any version up to and including 9.1.0.3)
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Confirm SmartConnect is configuredCheck the SmartConnect zone configuration by accessing the OneFS web UI under Network > SmartConnect or by running 'isi network adapters' and reviewing the SmartConnect settingsAffected if SmartConnect is actively configured and serving DNS responses on the cluster
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Verify SmartConnect service statusRun 'isi services' and look for the SmartConnect service, or check the SmartConnect process CPU usage via 'isi top' or similar system monitoring toolsAffected if The SmartConnect service is running and responding to DNS queries
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Check for DNS response issuesTest SmartConnect DNS responses using 'dig' or 'nslookup' against the SmartConnect zone IP and observe if responses are delayed or stalledAffected if DNS queries to SmartConnect hang or timeout while the SmartConnect process shows high CPU usage
You are affected if Dell PowerScale OneFS version 9.1.0.3 or lower is running with SmartConnect enabled and serving DNS responses.
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 dataUpgrade Dell PowerScale OneFS to version 9.1.0.4 or later, or apply the available Dell security patch to resolve the SmartConnect looping issue.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-21565 — 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-2021-21565 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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