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Epyc 7773x FirmwareOperating system · Amd

CVE-2021-26371

MEDIUM · 5.5 CVSS v3.1 Published 2023-05-09
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
A compromised or malicious ABL or UApp could send a SHA256 system call to the bootloader, which may result in exposure of ASP memory to userspace, potentially leading to information disclosure.

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

A compromised or malicious ABL (AMD Boot Loader) or UApp can send SHA256 system calls to the bootloader, which may expose AMD Secure Processor (ASP) memory contents to userspace, resulting in information disclosure.

MitigationEnsure only trusted and signed ABL/UApp code can execute; implement proper memory isolation to prevent ASP memory from being mapped to or accessible from userspace; validate all system calls from userspace to bootloader.

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 7773x FirmwareOperating system
Affected:< milanpi_1.0.0.6
Epyc 7763 FirmwareOperating system
Affected:< milanpi_1.0.0.6
Epyc 7713p FirmwareOperating system
Affected:< milanpi_1.0.0.6
Epyc 7713 FirmwareOperating system
Affected:< milanpi_1.0.0.6
Epyc 7663 FirmwareOperating system
Affected:< milanpi_1.0.0.6
Epyc 7643 FirmwareOperating system
Affected:< milanpi_1.0.0.6
Epyc 75f3 FirmwareOperating system
Affected:< milanpi_1.0.0.6
Epyc 7573x FirmwareOperating system
Affected:< milanpi_1.0.0.6

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 the AMD Epyc processor model
    Run 'dmidecode -t processor' or check BIOS/UEFI information to identify the exact processor model number
    Affected if The processor is one of the affected models: 7773x, 7763, 7713p, 7713, 7663, 7643, 75f3, or 7573x
  2. Check the current firmware version
    Use IPMI (e.g., 'ipmi sel list' or vendor-specific tools like amd-spis or AMD firmware update utilities) to retrieve the milanpi firmware version installed on the system
    Affected if Unable to retrieve firmware version or version information is missing
  3. Compare firmware version against the affected threshold
    Compare the installed milanpi firmware version to milanpi_1.0.0.6 using standard version comparison (e.g., 1.0.0.3, 1.0.0.5 are earlier; 1.0.0.6 and later are not affected)
    Affected if The installed firmware version is less than milanpi_1.0.0.6

The system is affected if it uses an AMD Epyc 7773x, 7763, 7713p, 7713, 7663, 7643, 75f3, or 7573x processor with firmware version earlier than milanpi_1.0.0.6.

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

Ensure only trusted and signed ABL/UApp code can execute; implement proper memory isolation to prevent ASP memory from being mapped to or accessible from userspace; validate all system calls from userspace to bootloader.

Recommended fix High confidence

milanpi_1.0.0.6 or later

  1. 1. Identify the current firmware version by checking the AMD Epyc processor system BIOS/UEFI or using AMD's firmware management tools
  2. 2. Download the updated firmware package from AMD's official support website for your specific Epyc 7003 series processor model (Milan)
  3. 3. Verify the firmware package integrity using checksums provided by AMD
  4. 4. Apply the firmware update following AMD's recommended procedures - this typically involves using the AMD firmware update utility or through the system BIOS/UEFI firmware update interface
  5. 5. After firmware update, verify the installed version shows milanpi_1.0.0.6 or later
  6. 6. Reboot the system to ensure the new firmware is properly loaded
Caveat Firmware updates carry inherent risk; ensure proper power backup during update and follow AMD's firmware update instructions precisely to avoid system instability

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

Fix this in Epyc 7773x Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation60.0 h
  • Testing30.0 h
  • Review / QA16.0 h
114.0 hours of engineering $19,780
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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-2021-26371 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