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Epyc 7001 FirmwareOperating system · Amd

CVE-2021-26403

MEDIUM · 6.5 CVSS v3.1 Published 2023-01-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
67/100
Remediation priority · Elevated
Zero-click

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 · unedited
Insufficient checks in SEV may lead to a malicious hypervisor disclosing the launch secret potentially resulting in compromise of VM confidentiality.

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 confidence

Insufficient validation checks in AMD SEV (Secure Encrypted Virtualization) could allow a malicious hypervisor to access the VM launch secret by exploiting improper handling of the encrypted memory encryption keys, breaking the confidentiality guarantees of SEV-protected virtual machines.

MitigationApply AMD SEV firmware/microcode updates and ensure hypervisor platforms (e.g., QEMU/KVM, Hyper-V with SEV) are updated to versions that include proper launch secret protection. Verify SEV加密功能正常工作 after patching.

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
Epyc 7001 FirmwareOperating system
Affected:< naplespi_1.0.0.e
Epyc 7251 FirmwareOperating system
Affected:< naplespi_1.0.0.e
Epyc 7261 FirmwareOperating system
Affected:< naplespi_1.0.0.e
Epyc 7281 FirmwareOperating system
Affected:< naplespi_1.0.0.e
Epyc 7301 FirmwareOperating system
Affected:< naplespi_1.0.0.e
Epyc 7351 FirmwareOperating system
Affected:< naplespi_1.0.0.e
Epyc 7351p FirmwareOperating system
Affected:< naplespi_1.0.0.e
Epyc 7371 FirmwareOperating system
Affected:< naplespi_1.0.0.e

CVSS 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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify AMD Epyc 7001 series processor
    Run 'lscpu' or check system BIOS/proc/cpuinfo to confirm the CPU model is one of: Amd Epyc 7001, 7251, 7261, 7281, 7301, 7351, 7351p, or 7371
    Affected if The system uses any of these specific Epyc processor models
  2. Verify SEV feature is enabled
    Check if SEV is active by inspecting /sys/class/kvm/kvm0/sev or running 'kvmstat -l' or checking hypervisor configuration for SEV support
    Affected if SEV (Secure Encrypted Virtualization) is enabled or configured on the system
  3. Check SEV firmware version
    Query the SEV firmware version using 'ls -la /dev/sev' or 'dmesg | grep -i sev' or through the hypervisor's SEV capability interface. Compare against naplespi_1.0.0.e
    Affected if The SEV firmware version is earlier than naplespi_1.0.0.e (e.g., 1.0.0.d or earlier)
  4. Confirm SEV is in use for protected VMs
    List running VMs and check which ones have SEV encryption enabled via 'virsh list --all' with 'virsh dominfo <vmname>' or hypervisor-specific commands
    Affected if Any SEV-encrypted virtual machines are running on the affected hardware with vulnerable firmware

A user is affected if they run SEV-protected VMs on an AMD Epyc 7001 series processor with firmware versions earlier than naplespi_1.0.0.e.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply AMD SEV firmware/microcode updates and ensure hypervisor platforms (e.g., QEMU/KVM, Hyper-V with SEV) are updated to versions that include proper launch secret protection. Verify SEV加密功能正常工作 after patching.

Recommended fix High confidence

naplespi_1.0.0.e

  1. Identify the specific Epyc 7001 series processor model in use
  2. Locate the appropriate firmware update from AMD's support website for the specific Epyc model
  3. Download the naplespi_1.0.0.e or later firmware version
  4. Apply the firmware update following AMD's standard BIOS/UEFI firmware update procedures for the server platform
  5. Reboot the system to complete the firmware update process
  6. Verify the firmware version has been updated to naplespi_1.0.0.e or later using system information utilities or BMC/IPMI interfaces
Caveat Firmware updates carry inherent risk and should be tested in a non-production environment first; ensure proper backup and rollback capabilities are available

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Epyc 7001 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-26403 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data