CVE-2021-26406Network attack vector

Host crash via malformed OCA certificate parsing

Published May 9, 2023 · Updated Jan 28, 2025

Certificate parsing in AMD SEV and SEV-ES on affected processors allows remote attackers to crash the virtualization host. The SEV firmware parses an OCA certificate without adequate validation, although AMD has not disclosed the missing check or malformed field. The target must use SEV or SEV-ES; exploitation interrupts the host, while SEV-SNP is not affected.

CVSS severity7.5
High
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Certificate parsing in AMD SEV and SEV-ES on affected processors allows remote attackers to crash the virtualization host. The SEV firmware parses an OCA certificate without adequate validation, although AMD has not disclosed the missing check or malformed field. The target must use SEV or SEV-ES; exploitation interrupts the host, while SEV-SNP is not affected.

The record

CVE
CVE-2021-26406
Published
May 9, 2023
Updated
Jan 28, 2025
Vendor
AMD
Product
Ryzen 2000 Series Mobile Processors (Raven Ridge, FP5)
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 28, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 vectornetwork
Required privilegesunauthenticated

What is affected?

AMD · Ryzen 2000 Series Mobile Processors (Raven Ridge, FP5)version=various
AMD · Athlon 3000 Series Mobile Processors with Radeon Graphics (Pollock)version=various
AMD · 2nd Gen AMD EPYC Processorsversion=various
AMD · Athlon 3000 Series Mobile Processors with Radeon Graphics (Dali/Dali ULP)version=various
Advanced Micro Devices, Inc. · AMD Ryzen 3000 Series Mobile Processors (Picasso)version=various
Advanced Micro Devices, Inc. · AMD Ryzen Threadripper PRO Processors (Castle Peak) WSversion=various
AMD · Ryzen 2000 Series Desktop Processors (Raven Ridge, AM4)version=various
Advanced Micro Devices, Inc. · 2nd Gen AMD Ryzen Threadripper Processors (Colfax)version=various
Advanced Micro Devices, Inc. · AMD Ryzen 3000 Series Desktop Processors (Matisse) AM4version=various
AMD · AMD Ryzen 5000 Series Desktop Processors (Vermeer, AM4)version=various
Advanced Micro Devices, Inc. · 3rd Gen AMD Ryzen Threadripper Processors (Castle Peak) HEDTversion=various
AMD · 1st Gen AMD EPYC Processorsversion=various
Advanced Micro Devices, Inc. · AMD Ryzen 2000 Series Desktop Processors (Pinnacle Ridge)version=various

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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