CVE-2021-26375

Service interruption via unchecked SMU GPIO index

Published May 11, 2022 · Updated Sep 17, 2024

Out-of-bounds access in the SMU firmware of AMD EPYC, Ryzen, and Athlon processors allows local users to interrupt service. The GPIO handler fails to validate a requested index before using it to access or update address space, permitting an invalid-address operation. Low-privileged local execution is required; AMD identifies denial of service but does not specify whether the interruption is a hang, crash, or reboot.

CVSS severity5.5
Medium
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

Out-of-bounds access in the SMU firmware of AMD EPYC, Ryzen, and Athlon processors allows local users to interrupt service. The GPIO handler fails to validate a requested index before using it to access or update address space, permitting an invalid-address operation. Low-privileged local execution is required; AMD identifies denial of service but does not specify whether the interruption is a hang, crash, or reboot.

The record

CVE
CVE-2021-26375
Published
May 11, 2022
Updated
Sep 17, 2024
Vendor
AMD
Product
AMD EPYC Processors
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 11, 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=various

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

AMD · AMD EPYC Processorsversion=various
AMD · AMD Athlon Processorsversion=various
AMD · AMD Ryzen Processorsversion=various

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/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.

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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 exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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