CVE-2021-26328

Guest memory corruption via unchecked SNP_INIT mode

Published Jan 10, 2023 · Updated Apr 9, 2025

Improper security-check implementation in AMD 3rd Gen EPYC processors allows local users to compromise SNP guest memory integrity. The SEV firmware processes SNP_INIT without verifying the CPU execution mode, allowing initialization under an invalid execution context. Exploitation requires local low-privileged access on an SEV-SNP host and can corrupt or disrupt protected guest memory, with no reported confidentiality impact.

CVSS severity4.4
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper security-check implementation in AMD 3rd Gen EPYC processors allows local users to compromise SNP guest memory integrity. The SEV firmware processes SNP_INIT without verifying the CPU execution mode, allowing initialization under an invalid execution context. Exploitation requires local low-privileged access on an SEV-SNP host and can corrupt or disrupt protected guest memory, with no reported confidentiality impact.

The record

CVE
CVE-2021-26328
Published
Jan 10, 2023
Updated
Apr 9, 2025
Vendor
Advanced Micro Devices, Inc.
Product
3rd Gen AMD EPYC Processors
Classifications
CWE-358, T1565.003
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=various

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Advanced Micro Devices, Inc. · 3rd Gen AMD EPYC Processorsversion=various

Published CVSS scores

4.4CISA ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-358Improperly Implemented Security Check for Standard
T1565.003Runtime Data Manipulation

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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