CVE-2021-38937
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 · uneditedIBM PowerVM Hypervisor FW940, FW950, and FW1010 could allow an authenticated user to cause the system to crash using a specially crafted IBMi Hypervisor call. IBM X-Force ID: 210894.
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 confidenceIBM PowerVM Hypervisor versions FW940, FW950, and FW1010 contain a denial-of-service vulnerability where an authenticated user can cause system crash by issuing specially crafted IBMi Hypervisor calls. The vulnerability allows a malicious authenticated user to trigger hypervisor failure, resulting in complete system unavailability.
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= fw940= fw950= fw1010CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 PowerVM hypervisor firmware versionRun 'lsmcode' on AIX, 'ioslevel' on VIOS, or access the HMC (Hardware Management Console) and navigate to the hypervisor firmware version information. On the HMC, go to Systems Management > Servers > select server > Properties > Licensed Internal Code (or similar depending on HMC version).Affected if The firmware version is exactly FW940, FW950, or FW1010.
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Confirm IBMi partition configuration existsOn the HMC, go to Systems Management > Servers > select server > Partitions > LPAR Configuration. Look for partitions running IBMi operating system. Alternatively, run 'lspar' or 'lssyscfg' commands via HMC command line.Affected if An IBMi partition is configured and active on the PowerVM hypervisor.
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Verify hypervisor administrative access controlsReview user access permissions on the HMC under Users and Groups. Check that only authorized personnel have hypervisor administrative privileges (HMC Super Administrator or Partition Administrator roles). Audit the list of users with access to manage IBMi partitions.Affected if Unrestricted or poorly monitored administrative access to IBMi partitions exists.
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Check for anomalous IBMi Hypervisor call loggingReview system logs on the IBMi partition for unusual hypervisor call patterns. Check IBMi service documentation for specific hypervisor call audit capabilities or contact IBM support for log analysis guidance.Affected if Unusual or repeated hypervisor calls are observed in IBMi logs, or no logging mechanism is in place.
You are affected if your PowerVM hypervisor firmware version is exactly FW940, FW950, or FW1010 AND you have IBMi partitions configured, since the attack requires authenticated IBMi users to issue the crafted hypervisor calls.
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 IBM-provided firmware updates for the affected PowerVM hypervisor versions. Additionally, restrict hypervisor administrative access to only trusted authenticated personnel and monitor for anomalous IBMi Hypervisor calls.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-38937 — 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-2021-38937 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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