CVE-2022-33986

SMRAM corruption via DMA parameter-buffer race

Published Nov 14, 2022 · Updated Apr 30, 2025

TOCTOU race in VariableRuntimeDxe in InsydeH2O allows local users to corrupt SMRAM through DMA changes to an SMI parameter buffer. The SMI handler checks the shared parameter buffer and later uses it without preventing DMA from changing its contents between those operations. Exploitation requires high privileges and DMA access to the buffer; a successful race corrupts protected SMRAM.

CVSS severity7.4
High
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU race in VariableRuntimeDxe in InsydeH2O allows local users to corrupt SMRAM through DMA changes to an SMI parameter buffer. The SMI handler checks the shared parameter buffer and later uses it without preventing DMA from changing its contents between those operations. Exploitation requires high privileges and DMA access to the buffer; a successful race corrupts protected SMRAM.

The record

CVE
CVE-2022-33986
Published
Nov 14, 2022
Updated
Apr 30, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-367, CAPEC-29, T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Nov 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 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?

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

6.4CISA ADP VulnrichmentCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
6.4NIST NVDCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
7.4Insyde SoftwareCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:L

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

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
CAPEC-29Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
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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