CVE-2021-26379
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 · uneditedInsufficient input validation of mailbox data in the SMU may allow an attacker to coerce the SMU to corrupt SMRAM, potentially leading to a loss of integrity and privilege escalation.
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 confidenceThis is a firmware vulnerability in AMD processors where the System Management Unit (SMU) fails to properly validate input data in its mailbox interface. This allows an attacker to manipulate the SMU to write arbitrary data into SMRAM (System Management RAM), corrupting the protected memory region used by System Management Mode. Successful exploitation can lead to integrity compromise and privilege escalation to SMM level.
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< milanpi_1.0.0.9< milanpi_1.0.0.9< milanpi_1.0.0.9< milanpi_1.0.0.9< milanpi_1.0.0.9< milanpi_1.0.0.9< milanpi_1.0.0.9< milanpi_1.0.0.9CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Identify the AMD Epyc processor modelUse commands such as `dmidecode -t processor` or `cat /proc/cpuinfo` to retrieve the processor identification. Alternatively, check the system BIOS or BMC (Baseboard Management Controller) for processor details.Affected if The processor model is one of the following: Epyc 72f3, 7313, 7313p, 7343, 7373x, 73f3, 7413, or 7443.
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Retrieve the current firmware versionCheck the BIOS/UEFI version or SMU firmware version through the BMC web interface, `dmidecode -s bios-version`, or vendor-specific tools such as AMD's SMU firmware check utility. The version string should be in the format milanpi_X.X.X.X.Affected if The firmware version is lower than milanpi_1.0.0.9, indicating the system is running a vulnerable firmware build.
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Verify the SMU mailbox interface is accessibleConfirm that the System Management Unit mailbox interface is enabled and accessible on the system. This may require checking BMC or BIOS settings related to SMU debugging or firmware debugging features.Affected if The SMU mailbox interface is enabled and accessible, allowing potential manipulation of SMU functions.
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Check SMRAM configurationInspect the System Management RAM (SMRAM) protection status. On Linux, tools such as `cat /sys/firmware/efi/smm_swap` or checking for SMM configuration in BIOS settings may reveal whether SMRAM locking is properly configured.Affected if SMRAM protection is not properly configured or is disabled, leaving the SMM memory region exposed to potential corruption.
A system is affected if it uses an AMD Epyc 72f3, 7313, 7313p, 7343, 7373x, 73f3, 7413, or 7443 processor with firmware version lower than milanpi_1.0.0.9 and has the SMU mailbox interface accessible.
Generated from the published advisory. Verify against your own configuration.
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 · scopedApply the AMD firmware/BIOS update that addresses this vulnerability. Verify that SMRAM protection mechanisms are properly configured and consider disabling SMM if not required, while ensuring all SMU firmware is patched to the vendor-recommended version.
milanpi_1.0.0.9 or later
- Identify the specific AMD Epyc processor model (72f3, 7313, 7313p, 7343, 7373x, 73f3, 7413, or 7443) in the affected system
- Obtain the firmware update from AMD's official support website or your system vendor's BIOS/firmware download page
- Verify the firmware version is milanpi_1.0.0.9 or later before applying
- Apply the firmware update following the system vendor's standard firmware/BIOS update procedure (typically via BMC/IPMI, BIOS flash utility, or platform-specific update tool)
- Reboot the system after the firmware update completes
- Confirm the installed firmware version is milanpi_1.0.0.9 or later to verify remediation
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,304.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-26379 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-26379 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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