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Epyc 7001 FirmwareOperating system · Amd

CVE-2021-46744

MEDIUM · 6.5 CVSS v3.1 Published 2022-05-11
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
An attacker with access to a malicious hypervisor may be able to infer data values used in a SEV guest on AMD CPUs by monitoring ciphertext values over time.

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

AMD SEV (Secure Encrypted Virtualization) allows a malicious hypervisor to infer data values in a SEV-protected guest by observing ciphertext patterns over time. This ciphertext timing/side-channel attack exploits the fact that identical plaintexts produce identical ciphertexts, enabling inference of sensitive data being processed in the encrypted VM.

MitigationDeploy AMD SEV-SNP (Secure Nested Paging) which provides stronger hypervisor isolation, or ensure hypervisor integrity through measured boot and verified boot chains to prevent malicious hypervisor code execution.

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:all versions
Epyc 7002 FirmwareOperating system
Affected:all versions
Epyc 7003 FirmwareOperating system
Affected:all versions
Epyc 7232p FirmwareOperating system
Affected:all versions
Epyc 7251 FirmwareOperating system
Affected:all versions
Epyc 7252 FirmwareOperating system
Affected:all versions
Epyc 7261 FirmwareOperating system
Affected:all versions
Epyc 7262 FirmwareOperating system
Affected:all versions

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. Check if AMD SEV is enabled for virtual machines
    Query the hypervisor or cloud provider to confirm SEV is in use. On KVM, check for 'sev' in the VM XML configuration (virsh dumpxml <vmname> | grep sev) or check /sys/kernel/security/sev for presence of SEV files. In cloud environments, verify the instance type supports and has SEV enabled.
    Affected if SEV is enabled and the hypervisor has the ability to observe ciphertext patterns over time
  2. Confirm SEV-SNP (Secure Nested Paging) is NOT in use
    Check the hypervisor or firmware documentation to determine if the SEV-SNP feature is active. On KVM, check kernel command line parameters or the SEV firmware capabilities. SEV-SNP provides protection that SEV alone lacks.
    Affected if The system uses SEV without SEV-SNP protection (SEV-SNP is not enumerated or enabled)
  3. Identify the AMD Epyc processor model and firmware version
    Use commands like 'dmidecode -t processor' to identify the CPU model, and check the system firmware/BIOS version. For cloud VMs, query the hypervisor for the underlying host CPU information. The affected models include Epyc 7001, 7002, 7003 series and specific models 7232p, 7251, 7252, 7261, 7262.
    Affected if The processor is an AMD Epyc 7001, 7002, or 7003 series, or specifically a 7232p, 7251, 7252, 7261, or 7262, with any firmware version, and SEV is enabled without SEV-SNP

A user is affected if they are running virtual machines with AMD SEV enabled (without SEV-SNP) on any of the listed AMD Epyc processor families, where the hypervisor could potentially observe ciphertext patterns over time to infer sensitive guest data.

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

Deploy AMD SEV-SNP (Secure Nested Paging) which provides stronger hypervisor isolation, or ensure hypervisor integrity through measured boot and verified boot chains to prevent malicious hypervisor code execution.

Recommended fix Moderate confidence

Firmware/BIOS update from AMD motherboard/system vendor (contact AMD or your hardware vendor for specific version)

  1. Contact your motherboard or system manufacturer to obtain a firmware/BIOS update that addresses the SEV vulnerability
  2. Verify that the update includes the AMD SEV security patch
  3. After applying the firmware update, verify SEV is functioning correctly by checking the PSP firmware version through AMD's tools or system BIOS information
  4. Ensure your hypervisor is updated to a version compatible with the patched firmware
Caveat Firmware updates may require system downtime and should be tested in a non-production environment first

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

Fix this in Epyc 7001 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing16.0 h
  • Review / QA8.0 h
56.0 hours of engineering $9,760
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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-2021-46744 in production — separate from our analysis above.

No notes yet

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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