dbcve.org
Epyc 7001 FirmwareOperating system · Amd

CVE-2021-26356

HIGH · 7.4 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 →
83/100
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
A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read to memory potentially resulting in S3 data corruption and 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 Time-Of-Check-Time-Of-Use (TOCTOU) race condition exists in the AMD Secure Processor (ASP) bootloader. An attacker can potentially tamper with the SPI ROM after data has been read to memory but before it is used, exploiting the window between the integrity check and data utilization. This allows modification of the bootloader or firmware, leading to S3 sleep state data corruption and information disclosure.

MitigationApply vendor-supplied BIOS/UEFI firmware updates that address the ASP bootloader TOCTOU vulnerability. Organizations should verify S3 resume integrity and ensure SPI ROM flash protections are enabled where available.

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:< naplespi_1.0.0.h
Epyc 7251 FirmwareOperating system
Affected:< naplespi_1.0.0.h
Epyc 7261 FirmwareOperating system
Affected:< naplespi_1.0.0.h
Epyc 7281 FirmwareOperating system
Affected:< naplespi_1.0.0.h
Epyc 7301 FirmwareOperating system
Affected:< naplespi_1.0.0.h
Epyc 7351 FirmwareOperating system
Affected:< naplespi_1.0.0.h
Epyc 7351p FirmwareOperating system
Affected:< naplespi_1.0.0.h
Epyc 7371 FirmwareOperating system
Affected:< naplespi_1.0.0.h

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 -s processor-version' or check system BIOS/UEFI information to confirm the specific Epyc 7001 series model (7251, 7261, 7281, 7301, 7351, 7351p, 7371, or 7001)
    Affected if The system uses any of the listed affected Epyc models (7251, 7261, 7281, 7301, 7351, 7351p, 7371, 7001)
  2. Check the AMD Secure Processor firmware version
    Use AMD firmware tools or contact AMD/OEM support to retrieve the ASP bootloader firmware version string. Look for a version identifier similar to 'naplespi' followed by a version number
    Affected if The ASP firmware version is earlier than naplespi_1.0.0.h (or the version cannot be determined but the processor is in the affected list)
  3. Determine if S3 sleep state is enabled
    Check system power management settings via 'powercfg /a' on Windows or 'cat /sys/power/state' on Linux to see if S3 (suspend-to-RAM) is available and enabled
    Affected if S3 sleep state is enabled and used on the system, as the vulnerability specifically exploits the S3 resume sequence
  4. Verify SPI ROM flash protection status
    Check BIOS/UEFI settings for SPI ROM write protection or flash protection status. On some systems, this can be inspected via 'dmidecode' or OEM management tools
    Affected if SPI ROM flash protections are disabled or not configured, leaving the ROM modifiable during the vulnerable window

The environment is affected if the system uses an AMD Epyc 7001 series processor from the list, has ASP bootloader firmware version earlier than naplespi_1.0.0.h, and uses S3 sleep state with unprotected SPI ROM.

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 vendor-supplied BIOS/UEFI firmware updates that address the ASP bootloader TOCTOU vulnerability. Organizations should verify S3 resume integrity and ensure SPI ROM flash protections are enabled where available.

Recommended fix High confidence

naplespi_1.0.0.h or later

  1. Obtain the AMD Epyc 7001 series firmware update (naplespi_1.0.0.h or later) from the official AMD support website or AMD's secure firmware distribution channel
  2. Follow AMD's documented firmware update procedure for Epyc 7001 processors (typically requires system administrator access and may require server downtime)
  3. Apply the firmware update to all affected Epyc 7001 series processors in the environment
  4. Verify the installed firmware version matches naplespi_1.0.0.h or later using AMD's system management tools
  5. Confirm the S3 resume functionality works correctly post-update to ensure no data corruption

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
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA4.0 h
40.0 hours of engineering $7,000
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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-2021-26356 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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