CVE-2023-39284

Firmware variable manipulation via unsanitized SMI arguments

Published Nov 2, 2023 · Updated Sep 5, 2024

Firmware variable manipulation in Insyde InsydeH2O kernels 5.2 through 5.6 allows local users with high privileges to alter UEFI variables. The IhisiServicesSmm SMI handler forwards attacker-controlled arguments to SmmSetVariable() without filtering or sanitization. High local privileges and no user interaction are required; successful exploitation modifies firmware variables across the SMM trust boundary.

CVSS severity6.1
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Firmware variable manipulation in Insyde InsydeH2O kernels 5.2 through 5.6 allows local users with high privileges to alter UEFI variables. The IhisiServicesSmm SMI handler forwards attacker-controlled arguments to SmmSetVariable() without filtering or sanitization. High local privileges and no user interaction are required; successful exploitation modifies firmware variables across the SMM trust boundary.

The record

CVE
CVE-2023-39284
Published
Nov 2, 2023
Updated
Sep 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1542.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Nov 2, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 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

6.1Insyde SoftwareCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:H/A:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

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

T1542.001Pre-OS Boot: System Firmware

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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