CVE-2021-26345

Denial of service via unvalidated APCB token

Published Nov 14, 2023 · Updated Aug 3, 2024

Out-of-bounds read in AMD EPYC PI firmware allows attackers to interrupt 2nd through 4th Gen and Embedded 7002/7003 systems. APCB processing fails to validate a token value before using it for a memory read, allowing a tampered token to drive the read beyond its intended bounds. Exploitation requires high privileges on server processors or physical access on embedded processors, and the resulting read can interrupt the system.

CVSS severity1.9
Low
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in AMD EPYC PI firmware allows attackers to interrupt 2nd through 4th Gen and Embedded 7002/7003 systems. APCB processing fails to validate a token value before using it for a memory read, allowing a tampered token to drive the read beyond its intended bounds. Exploitation requires high privileges on server processors or physical access on embedded processors, and the resulting read can interrupt the system.

The record

CVE
CVE-2021-26345
Published
Nov 14, 2023
Updated
Aug 3, 2024
Vendor
Advanced Micro Devices, Inc.
Product
3rd Gen AMD EPYC Processors
Classifications
CWE-125, T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Nov 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=various

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Advanced Micro Devices, Inc. · 3rd Gen AMD EPYC Processorsversion=various
Advanced Micro Devices, Inc. · AMD EPYC Embedded 7003 Series Processorsversion=various
Advanced Micro Devices, Inc. · AMD EPYC Embedded 7002 Series Processorsversion=various
Advanced Micro Devices, Inc. · 4th Gen AMD EPYC Processorsversion=various
Advanced Micro Devices, Inc. · 2nd Gen AMD EPYC Processorsversion=various

Published CVSS scores

1.9Advanced Micro Devices, Inc.CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L
4.9NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:H/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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
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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