dbcve.org
Epyc 7601 FirmwareOperating system · Amd

CVE-2021-26320

MEDIUM · 5.5 CVSS v3.1 Published 2021-11-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
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 validation of the AMD SEV Signing Key (ASK) in the SEND_START command in the SEV Firmware may allow a local authenticated attacker to perform a denial of service of the PSP

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

The vulnerability exists in AMD SEV (Secure Encrypted Virtualization) firmware where the SEND_START command does not properly validate the AMD SEV Signing Key (ASK). This allows a local authenticated attacker to cause a denial of service against the Platform Security Processor (PSP), which is a dedicated security processor in AMD systems.

MitigationApply the AMD firmware update that addresses this vulnerability. Contact AMD for the specific firmware version containing the fix and follow their update procedures for SEV-enabled systems.

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 7601 FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g
Epyc 7551p FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g
Epyc 7551 FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g
Epyc 7501 FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g
Epyc 7451 FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g
Epyc 7401 FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g
Epyc 7371 FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g
Epyc 7351p FirmwareOperating system
Affected:< naplespi-sp3_1.0.0.g

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
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/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 checks

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

  1. Identify the CPU model
    Run `cat /proc/cpuinfo | grep 'model name'` or `dmidecode -t processor | grep -E 'Version|Model'` to confirm the processor is an AMD Epyc 7000 series (7601, 7551p, 7551, 7501, 7451, 7401, 7371, or 7351p)
    Affected if The installed CPU is NOT one of the listed Epyc 7000 series models, then this CVE does not apply
  2. Check SEV firmware version
    Run `dmesg | grep -i sev` or check `/sys/firmware/sev/` to locate the PSP firmware version string. Compare the version to 'naplespi-sp3_1.0.0.g' - versions before this string (lexicographically lower) are affected
    Affected if The SEV firmware version is < naplespi-sp3_1.0.0.g (e.g., older Naples SPI firmware)
  3. Verify SEV is enabled in the system
    Check if SEV is active by running `kvm-ok 2>/dev/null` or inspecting `dmesg` for messages containing 'SEV' or 'AMD Secure Encrypted Virtualization'. Also check `ls /sys/firmware/sev/` to confirm the SEV interface exists
    Affected if SEV is not enabled or the SEV firmware interface is not present, the specific SEND_START command flaw cannot be triggered

You are affected if you are running one of the listed Epyc 7000 series processors with SEV firmware version older than naplespi-sp3_1.0.0.g and SEV is enabled in your system

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 the AMD firmware update that addresses this vulnerability. Contact AMD for the specific firmware version containing the fix and follow their update procedures for SEV-enabled systems.

Recommended fix Moderate confidence

naplespi-sp3_1.0.0.g or later

  1. 1. Identify the current firmware version of the AMD Epyc processor by checking the system BIOS/UEFI or using the AMD PSP firmware tools
  2. 2. Download the latest AMD SEV firmware update from the official AMD support website (www.amd.com) for your specific Epyc processor model
  3. 3. Update the AMD SEV (Secure Encrypted Virtualization) firmware to version naplespi-sp3_1.0.0.g or later
  4. 4. Verify the firmware update was successful by checking the new firmware version
  5. 5. Reboot the system to ensure the new firmware is fully initialized
Caveat Firmware updates may require system downtime and should be tested in a non-production environment first; ensure backup of system state before applying

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

Fix this in Epyc 7601 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-2021-26320 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