CVE-2021-26323

Memory-integrity loss via unvalidated SEV commands

Published Nov 16, 2021 · Updated Sep 16, 2024

Improper input validation in AMD SEV firmware on 3rd Gen AMD EPYC processors allows local users to compromise SNP memory integrity. The SEV firmware fails to validate SEV commands submitted while Secure Nested Paging is active, allowing invalid command data to affect protected memory state. Exploitation requires local low-privileged access on a system actively using SNP; the published consequence is limited to memory-integrity loss.

CVSS severity7.8
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in AMD SEV firmware on 3rd Gen AMD EPYC processors allows local users to compromise SNP memory integrity. The SEV firmware fails to validate SEV commands submitted while Secure Nested Paging is active, allowing invalid command data to affect protected memory state. Exploitation requires local low-privileged access on a system actively using SNP; the published consequence is limited to memory-integrity loss.

The record

CVE
CVE-2021-26323
Published
Nov 16, 2021
Updated
Sep 16, 2024
Vendor
Advanced Micro Devices, Inc.
Product
3rd Gen AMD EPYC Processors
Classifications
CWE-20
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <MilanPI-SP3_1.0.0.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Advanced Micro Devices, Inc. · 3rd Gen AMD EPYC Processorsversion=unspecified <MilanPI-SP3_1.0.0.4

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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