CVE-2021-33164

Firmware privilege escalation via SMRAM validation race

Published Nov 11, 2022 · Updated Aug 3, 2024

Improper access control in Intel NUC BIOS firmware before INWHL357.0046 allows local users with administrative privileges to execute SMM code. A race between SMI-handler validation and use of SMRAM-backed communication data lets DMA overwrite checked contents before execution. Administrative access is required; successful exploitation crosses the operating-system boundary and can bypass boot protections, install persistent firmware-level code, or permanently stop the system.

CVSS severity8.2
High
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Intel NUC BIOS firmware before INWHL357.0046 allows local users with administrative privileges to execute SMM code. A race between SMI-handler validation and use of SMRAM-backed communication data lets DMA overwrite checked contents before execution. Administrative access is required; successful exploitation crosses the operating-system boundary and can bypass boot protections, install persistent firmware-level code, or permanently stop the system.

The record

CVE
CVE-2021-33164
Published
Nov 11, 2022
Updated
Aug 3, 2024
Vendor
Intel Corporation
Product
Intel NUC
Classifications
T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Nov 11, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <nwhl357.0046

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Intel Corporation · Intel NUCversion=0 <nwhl357.0046

Published CVSS scores

8.2Intel CorporationCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
6.7NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/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.

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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

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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