CVE-2021-46775

Physical code execution via ABL memory overwrite

Published May 9, 2023 · Updated Jan 28, 2025

Improper input validation in AMD EPYC AGESA ABL allows physically proximate attackers to overwrite memory and execute code. AMD identifies only the AGESA Boot Loader locus; it does not disclose which input is accepted without validation or how that input selects arbitrary memory destinations. Physical access to an affected 2nd or 3rd Gen EPYC server is required, and successful exploitation compromises platform memory integrity and permits code execution.

CVSS severity6.8
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in AMD EPYC AGESA ABL allows physically proximate attackers to overwrite memory and execute code. AMD identifies only the AGESA Boot Loader locus; it does not disclose which input is accepted without validation or how that input selects arbitrary memory destinations. Physical access to an affected 2nd or 3rd Gen EPYC server is required, and successful exploitation compromises platform memory integrity and permits code execution.

The record

CVE
CVE-2021-46775
Published
May 9, 2023
Updated
Jan 28, 2025
Vendor
Advanced Micro Devices, Inc.
Product
3rd Gen AMD EPYC Processors
Classifications
CWE-20
Attack vector
physical
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

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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 vectorphysical
Required privilegesunauthenticated

What is affected?

Advanced Micro Devices, Inc. · 3rd Gen AMD EPYC Processorsversion=various
Advanced Micro Devices, Inc. · 2nd Gen AMD EPYC Processorsversion=various

Published CVSS scores

6.8CISA-ADPCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation

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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