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Epyc 7f72 FirmwareOperating system · Amd

CVE-2021-26338

HIGH · 7.5 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 →
84/100
Remediation priority · High
Remotely reachable No privileges 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
Improper access controls in System Management Unit (SMU) may allow for an attacker to override performance control tables located in DRAM resulting in a potential lack of system resources.

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

Improper access controls in AMD's System Management Unit (SMU) allow an attacker to modify performance control tables stored in DRAM, potentially causing system resource starvation or instability.

MitigationApply AMD-provided firmware/microcode updates and associated BIOS/UEFI updates from motherboard vendors to remediate the SMU access control vulnerability.

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 7f72 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 7f52 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 7f32 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 7h12 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 7742 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 7702 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 7702p FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 7662 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c

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
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 checks

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

  1. Identify the CPU model
    Run 'dmidecode -s processor-version' or check /proc/cpuinfo to identify the exact AMD Epyc processor model
    Affected if The processor is one of the following: Epyc 7f72, 7f52, 7f32, 7h12, 7742, 7702, 7702p, or 7662
  2. Check SMU firmware version
    Use vendor-specific tools (such as AMD's SMU firmware version utilities) or check via IPMI/BMC interfaces if available to retrieve the System Management Unit firmware version string
    Affected if The SMU firmware version string is present and is less than romepi-sp3_1.0.0.c (for example, an earlier build of the same firmware family)
  3. Verify performance control table configuration
    Inspect system management logs or use AMD diagnostic tools to check the configuration and accessibility of SMU performance control tables stored in DRAM
    Affected if Performance control tables in DRAM are readable or modifiable by non-privileged software contexts due to missing access controls in the SMU

You are affected if you are running any of the listed Epyc models with SMU firmware versions earlier than romepi-sp3_1.0.0.c.

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-provided firmware/microcode updates and associated BIOS/UEFI updates from motherboard vendors to remediate the SMU access control vulnerability.

Recommended fix High confidence

romepi-sp3_1.0.0.c or later SMU firmware

  1. 1. Identify the current SMU firmware version on the affected AMD Epyc processor by checking the system BIOS/UEFI or using AMD's system information tools
  2. 2. Download the updated firmware romepi-sp3_1.0.0.c or later from AMD's official support website for your specific Epyc model
  3. 3. Apply the firmware update through the appropriate method: either via BIOS/UEFI update (flashing the system BIOS which includes SMU firmware) or using AMD's dedicated firmware update utilities
  4. 4. Verify the firmware has been successfully updated by checking the SMU firmware version after the update process completes
  5. 5. Reboot the system to ensure the new SMU firmware is properly initialized
Caveat Firmware updates carry inherent risks; ensure proper power backup during the update process and verify system stability after applying the update

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

Fix this in Epyc 7f72 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,680
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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-2021-26338 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