CVE-2021-26342

SEV guest-memory disclosure via stale TLB translations

Published May 11, 2022 · Updated Sep 16, 2024

TLB-flush failure in AMD EPYC SEV guest VMs allows local users to disclose guest memory via stale address translations. After a sequence that creates a new VMCB, the CPU fails to invalidate the TLB, so microcode reuses stale translations for SEV memory accesses. Exploitation requires local low-privileged access to a standard SEV guest; SEV-ES and SEV-SNP guests are not affected.

CVSS severity3.3
Low
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TLB-flush failure in AMD EPYC SEV guest VMs allows local users to disclose guest memory via stale address translations. After a sequence that creates a new VMCB, the CPU fails to invalidate the TLB, so microcode reuses stale translations for SEV memory accesses. Exploitation requires local low-privileged access to a standard SEV guest; SEV-ES and SEV-SNP guests are not affected.

The record

CVE
CVE-2021-26342
Published
May 11, 2022
Updated
Sep 16, 2024
Vendor
AMD
Product
AMD EPYC Processors
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 11, 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?

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  1. Affected versionversion=various

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

AMD · AMD EPYC Processorsversion=various

Published CVSS scores

2.1NISTAV:L/AC:L/Au:N/C:P/I:N/A:N
3.3NISTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/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 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

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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