CVE-2021-41842

SMM code execution via unchecked communication buffer

Published Jan 5, 2022 · Updated Aug 4, 2024

Code execution in AtaLegacySmm in affected Insyde InsydeH2O 5.0 through 5.5 kernels allows local users with administrative privileges to run code in SMM. The AtaLegacySmm SMI handler accepts a caller-supplied communication buffer without validating it before privileged SMM processing. Administrative operating-system access is required; successful exploitation executes code above the OS kernel and can undermine firmware-backed platform protections.

CVSS severity8.2
High
EPSS probability1.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code execution in AtaLegacySmm in affected Insyde InsydeH2O 5.0 through 5.5 kernels allows local users with administrative privileges to run code in SMM. The AtaLegacySmm SMI handler accepts a caller-supplied communication buffer without validating it before privileged SMM processing. Administrative operating-system access is required; successful exploitation executes code above the OS kernel and can undermine firmware-backed platform protections.

The record

CVE
CVE-2021-41842
Published
Jan 5, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Jan 5, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
8.2Insyde SoftwareCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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