CVE-2020-12966Public exploit

Guest key disclosure via VMSA ciphertext side channel

Published Feb 4, 2022 · Updated Sep 17, 2024

Information disclosure in AMD EPYC Processors with SEV, SEV-ES, or SEV-SNP allows local users controlling the hypervisor to read guest data. SEV memory encryption leaves identical plaintext at a fixed physical address represented by identical ciphertext, while permitting the hypervisor to read encrypted VMSA memory and infer register values. Hypervisor control and an SEV-enabled guest are required; demonstrated attacks recover RSA private keys and ECDSA nonces from guest cryptographic operations.

CVSS severity5.5
Medium
EPSS probability0.31%
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 EPYC Processors with SEV, SEV-ES, or SEV-SNP allows local users controlling the hypervisor to read guest data. SEV memory encryption leaves identical plaintext at a fixed physical address represented by identical ciphertext, while permitting the hypervisor to read encrypted VMSA memory and infer register values. Hypervisor control and an SEV-enabled guest are required; demonstrated attacks recover RSA private keys and ECDSA nonces from guest cryptographic operations.

The record

CVE
CVE-2020-12966
Published
Feb 4, 2022
Updated
Sep 17, 2024
Vendor
AMD
Product
AMD EPYC Processors
Classifications
CWE-200, T1552.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 4, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=unspecified <undefined

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

AMD · AMD EPYC Processorsversion=unspecified <undefined

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
2.1NIST NVDAV:L/AC:L/Au:N/C:P/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.

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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 exploitPublished

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
T1552.004Unsecured Credentials: Private Keys

Public exploit references

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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