CVE-2021-26373

Service interruption via insufficient SMU bounds checks

Published May 11, 2022 · Updated Sep 16, 2024

Improper input validation in the SMU of affected AMD EPYC, Ryzen, and Athlon processors allows local users to interrupt service. The SMU fails to enforce bounds on an undisclosed input, causing system voltage to enter a malfunctioning state. Low-privileged local access is required; exploitation can deny resources or stop the host service, but AMD has not disclosed the exact input path or terminal failure mode.

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

Improper input validation in the SMU of affected AMD EPYC, Ryzen, and Athlon processors allows local users to interrupt service. The SMU fails to enforce bounds on an undisclosed input, causing system voltage to enter a malfunctioning state. Low-privileged local access is required; exploitation can deny resources or stop the host service, but AMD has not disclosed the exact input path or terminal failure mode.

The record

CVE
CVE-2021-26373
Published
May 11, 2022
Updated
Sep 16, 2024
Vendor
AMD
Product
AMD EPYC Processors
Classifications
CWE-20, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 11, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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 vectorlocal
Required privilegesauthenticated

What is affected?

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

Published CVSS scores

4.9NIST National Vulnerability DatabaseAV:L/AC:L/Au:N/C:N/I:N/A:C
5.5NIST National Vulnerability DatabaseCVSS: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.

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
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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