CVE-2021-26406
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 · uneditedInsufficient validation in parsing Owner's Certificate Authority (OCA) certificates in SEV (AMD Secure Encrypted Virtualization) and SEV-ES user application can lead to a host crash potentially resulting in denial of service.
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 confidenceA vulnerability in AMD SEV and SEV-ES allows a guest virtual machine to trigger insufficient validation when parsing the Owner's Certificate Authority (OCA) certificates. This can cause a host crash, resulting in denial of service for the entire virtualization platform.
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= romepi_1.0.0.a= romepi_1.0.0.a= romepi_1.0.0.a= romepi_1.0.0.a= romepi_1.0.0.a= romepi_1.0.0.a= romepi_1.0.0.a= romepi_1.0.0.aCVSS 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
- High
CVSS:3.1/AV:N/AC:L/PR:N/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 the AMD Epyc processor modelRun 'lscpu' or check /proc/cpuinfo to identify the CPU model (e.g., Epyc 7232p, 7252, 7262, 7272, 7282, 7302, 7302p, 7352)Affected if The processor is one of the listed models (7232p, 7252, 7262, 7272, 7282, 7302, 7302p, 7352)
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Check the SEV firmware versionOn the hypervisor host, query the AMD SEV firmware version via 'cat /sys/class/misc/sev_firmware/version' or use the AMD SEV tool if available. Compare against romepi_1.0.0.aAffected if The firmware version equals romepi_1.0.0.a exactly
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Verify SEV or SEV-ES is enabledCheck hypervisor configuration: for KVM, look for 'sev' or 'sev-es' in the VM XML definition or libvirt configuration. For Hyper-V, check SEV settings. Also check /sys/class/misc/sev_firmware/ for presence of SEV support.Affected if SEV or SEV-ES is enabled and active on any virtual machine on the host
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Inspect OCA certificate configurationExamine the SEV platform initialization files and OCA certificate paths on the hypervisor host. Check if custom OCA certificates are loaded via 'ls -la /etc/sev*' or similar paths depending on hypervisor.Affected if Custom OCA certificates are configured or loaded on the SEV platform
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Check hypervisor logs for crashesReview hypervisor logs (dmesg, /var/log/libvirt/qemu/*.log for KVM, or Hyper-V event logs) for any host crashes or SEV-related errors around the time of VM startup with SEV enabled.Affected if Host crashes have occurred that coincide with SEV-enabled VM operations
You are affected if you run any of the listed AMD Epyc processors with firmware version romepi_1.0.0.a and have SEV or SEV-ES enabled on your virtualization platform.
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 AMD-provided firmware updates and patches for SEV/SEV-ES that address certificate validation. Verify OCA certificate integrity before parsing and ensure hypervisor components handling SEV are updated.
- 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-2021-26406 — 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-2021-26406 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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- Version or environment caveats, and links to real fixes
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