CVE-2021-26336

SMU hang via insufficient bounds checking

Published Nov 16, 2021 · Updated Sep 16, 2024

Improper bounds checking in SMU firmware for AMD Ryzen and Athlon Series allows local users to hang the SMU via invalid memory access. The SMU accepts an out-of-range value without adequate validation and performs an invalid memory access or update that stops request processing. Low-privileged local access is required; the hang prevents the SMU from servicing further requests from other platform components.

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 bounds checking in SMU firmware for AMD Ryzen and Athlon Series allows local users to hang the SMU via invalid memory access. The SMU accepts an out-of-range value without adequate validation and performs an invalid memory access or update that stops request processing. Low-privileged local access is required; the hang prevents the SMU from servicing further requests from other platform components.

The record

CVE
CVE-2021-26336
Published
Nov 16, 2021
Updated
Sep 16, 2024
Vendor
AMD
Product
AMD Ryzen Series
Classifications
CWE-119, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 16, 2021CVE 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 Ryzen Seriesversion=various
AMD · AMD Athlon Seriesversion=various

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.9NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:C

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-119Improper Restriction of Operations within the Bounds of a Memory Buffer
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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