CVE-2021-4212

Code execution via improperly validated SMI input

Published Apr 22, 2022 · Updated Aug 3, 2024

Improper input validation in Lenovo notebook BIOS firmware allows local users with elevated privileges to execute arbitrary code. The SMI callback in the Legacy BIOS mode driver accepts improperly validated input, enabling attacker-controlled execution in the firmware context. Exploitation requires local access and elevated privileges on an affected Lenovo notebook, and the disclosed consequence is arbitrary code execution rather than a remote attack path.

CVSS severity6.7
Medium
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 Lenovo notebook BIOS firmware allows local users with elevated privileges to execute arbitrary code. The SMI callback in the Legacy BIOS mode driver accepts improperly validated input, enabling attacker-controlled execution in the firmware context. Exploitation requires local access and elevated privileges on an affected Lenovo notebook, and the disclosed consequence is arbitrary code execution rather than a remote attack path.

The record

CVE
CVE-2021-4212
Published
Apr 22, 2022
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Apr 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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

6.7Lenovo Group Ltd.CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
7.2NVDAV:L/AC:L/Au:N/C:C/I:C/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.

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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

CWE-20Improper Input Validation

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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