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Epyc 7003 FirmwareOperating system · Amd

CVE-2021-26337

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 DRAM address validation in System Management Unit (SMU) may result in a DMA read from invalid DRAM address to SRAM resulting in SMU not servicing further requests.

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 DRAM address validation in AMD's System Management Unit (SMU) allows a DMA read from an invalid DRAM address to write into SRAM, causing the SMU to stop servicing further requests and resulting in a denial-of-service condition.

MitigationApply AMD-provided SMU firmware updates to address the address validation vulnerability; until patches are available, monitor for anomalous SMU behavior and ensure systems are not exposed to untrusted DMA-capable devices.

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 7003 FirmwareOperating system
Affected:< milanpi-sp3_1.0.0.4
Epyc 7002 FirmwareOperating system
Affected:< romepi-sp3_1.0.0.c
Epyc 72f3 FirmwareOperating system
Affected:< milanpi-sp3_1.0.0.4
Epyc 7313 FirmwareOperating system
Affected:< milanpi-sp3_1.0.0.4
Epyc 7313p FirmwareOperating system
Affected:< milanpi-sp3_1.0.0.4
Epyc 7343 FirmwareOperating system
Affected:< milanpi-sp3_1.0.0.4
Epyc 73f3 FirmwareOperating system
Affected:< milanpi-sp3_1.0.0.4
Epyc 7413 FirmwareOperating system
Affected:< milanpi-sp3_1.0.0.4

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
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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 processor model
    Use 'dmidecode -t processor' or check system documentation to identify the specific AMD Epyc model. Confirm it matches one of the affected models: Epyc 7003, 7002, 72f3, 7313, 7313p, 7343, 73f3, or 7413.
    Affected if The system uses an AMD Epyc 7003, 7002, 72f3, 7313, 7313p, 7343, 73f3, or 7413 processor.
  2. Retrieve SMU firmware version
    Access the BMC/IPMI interface or use 'ipmitool' commands to query the System Management Unit firmware version. The exact command varies by BMC vendor but typically involves 'ipmitool raw' or checking the BMC firmware inventory.
    Affected if The installed SMU firmware version is earlier than milanpi-sp3_1.0.0.4 (for Epyc 7003, 72f3, 7313, 7313p, 7343, 73f3, 7413) or earlier than romepi-sp3_1.0.0.c (for Epyc 7002).
  3. Check for anomalous SMU behavior
    Monitor system logs via BMC (IPMI, SEL logs) or operating system logs for SMU-related errors, timeouts, or failure messages indicating the SMU has stopped servicing requests.
    Affected if SMU is unresponsive, returning errors, or logs show SMU failure events.
  4. Assess DMA device exposure
    Review PCIe device inventory (lspci) and system configuration to determine if untrusted or external DMA-capable devices have access to the system.
    Affected if Untrusted DMA-capable PCIe devices are attached and could potentially trigger the invalid DMA read condition.

A user is affected if they run an AMD Epyc 7002/7003/72f3/7313/7313p/7343/73f3/7413 processor with SMU firmware below the indicated thresholds and have untrusted DMA-capable devices with system access.

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 SMU firmware updates to address the address validation vulnerability; until patches are available, monitor for anomalous SMU behavior and ensure systems are not exposed to untrusted DMA-capable devices.

Recommended fix High confidence

milanpi-sp3_1.0.0.4 (for Epyc 7003/72f3/7313/7313p/7343/73f3/7413) or romepi-sp3_1.0.0.c (for Epyc 7002)

  1. Identify the exact AMD Epyc processor model (7002 series/Rome or 7003 series/Milan or other listed variants)
  2. Download the corresponding firmware update from AMD's support website: milanpi-sp3_1.0.0.4 for Milan-based processors or romepi-sp3_1.0.0.c for Rome-based processors
  3. Apply the firmware update using the server manufacturer's recommended SMU firmware update procedure, typically via BMC/IPMI or dedicated firmware update utility
  4. Reboot the system to ensure the new SMU firmware is loaded and verify the update was successful
Caveat Firmware updates carry inherent risk; ensure backup and follow vendor update procedures carefully

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

Fix this in Epyc 7003 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2021-26337 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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