CVE-2021-26316

SMM code execution via unvalidated BIOS communication buffer

Published Jan 10, 2023 · Updated Apr 9, 2025

Improper input validation in BIOS firmware on affected AMD processors allows local users to execute arbitrary code in System Management Mode. The BIOS fails to validate both the communication buffer and the requested communication service before acting on attacker-controlled data, allowing the buffer to be tampered with. Low-privileged local access is required, and successful exploitation runs code in the highly privileged SMM context.

CVSS severity7.8
High
EPSS probability0.26%
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 BIOS firmware on affected AMD processors allows local users to execute arbitrary code in System Management Mode. The BIOS fails to validate both the communication buffer and the requested communication service before acting on attacker-controlled data, allowing the buffer to be tampered with. Low-privileged local access is required, and successful exploitation runs code in the highly privileged SMM context.

The record

CVE
CVE-2021-26316
Published
Jan 10, 2023
Updated
Apr 9, 2025
Vendor
AMD
Product
AMD EPYC 7002 Series Processors
Classifications
CWE-20, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 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 vectorlocal
Required privilegesauthenticated

What is affected?

AMD · AMD EPYC 7002 Series Processorsversion=Various
AMD · AMD Ryzen 2000 Series Processorsversion=various
AMD · AMD Ryzen 5000 Series Processorsversion=various
AMD · AMD Ryzen 3000 Series Processorsversion=various
AMD · AMD EPYC 7001 Series Processorsversion=various
AMD · AMD EPYC 7003 Series Processorsversion=various

Published CVSS scores

7.8NISTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1068Exploitation for Privilege Escalation

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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