CVE-2021-26403

VM launch-secret disclosure via insufficient SEV checks

Published Jan 10, 2023 · Updated Apr 8, 2025

Information disclosure in AMD SEV on first- and second-generation EPYC processors allows local users to obtain a VM launch secret. AMD states that SEV performs insufficient checks during launch-secret handling but does not identify the checked value or validation path. Exploitation requires control of the host hypervisor and affects confidentiality of SEV or SEV-ES guests, not SEV-SNP guests.

CVSS severity6.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in AMD SEV on first- and second-generation EPYC processors allows local users to obtain a VM launch secret. AMD states that SEV performs insufficient checks during launch-secret handling but does not identify the checked value or validation path. Exploitation requires control of the host hypervisor and affects confidentiality of SEV or SEV-ES guests, not SEV-SNP guests.

The record

CVE
CVE-2021-26403
Published
Jan 10, 2023
Updated
Apr 8, 2025
Vendor
AMD
Product
2nd Gen AMD EPYC Processors
Classifications
CWE-345
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jan 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 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?

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

  1. Affected versionversion=various

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

AMD · 2nd Gen AMD EPYC Processorsversion=various
AMD · 1st Gen AMD EPYC Processorsversion=various

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
6.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity

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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