CVE-2021-26408

Guest migration compromise via unvalidated elliptic-curve points

Published May 10, 2022 · Updated Sep 16, 2024

Elliptic-curve validation failure in AMD SEV-legacy firmware allows local users to compromise guest migration integrity or confidentiality. The firmware accepts elliptic-curve points during SEV-legacy guest migration without sufficient validation; AMD has not disclosed the exact command or check. Exploitation requires low-privileged local access and an SEV-legacy migration, and it exposes or alters guest state without affecting availability.

CVSS severity7.1
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Elliptic-curve validation failure in AMD SEV-legacy firmware allows local users to compromise guest migration integrity or confidentiality. The firmware accepts elliptic-curve points during SEV-legacy guest migration without sufficient validation; AMD has not disclosed the exact command or check. Exploitation requires low-privileged local access and an SEV-legacy migration, and it exposes or alters guest state without affecting availability.

The record

CVE
CVE-2021-26408
Published
May 10, 2022
Updated
Sep 16, 2024
Vendor
AMD
Product
2nd Gen AMD EPYC Processors
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 10, 2022CVE 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 <RomePI-SP3_1.0.0.C

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

AMD · 2nd Gen AMD EPYC Processorsversion=unspecified <RomePI-SP3_1.0.0.C
AMD · 1st Gen AMD EPYC Processorsversion=unspecified <NaplesPI-SP3_1.0.0.G

Published CVSS scores

6.6NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:N
7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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