CVE-2023-39539Public exploit

Firmware code execution via malformed PNG dimensions

Published Dec 6, 2023 · Updated Dec 16, 2025

Improper PNG validation in AMI Aptio V before BKS_5.34 allows local users to execute code with UEFI firmware privileges. The AMITSE PNG decoder multiplies attacker-controlled image dimensions without checking for integer overflow, then writes decoded data beyond the undersized allocation. Exploitation requires administrative access to flash a crafted logo and a reboot; successful corruption diverts execution during firmware boot.

CVSS severity7.5
High
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper PNG validation in AMI Aptio V before BKS_5.34 allows local users to execute code with UEFI firmware privileges. The AMITSE PNG decoder multiplies attacker-controlled image dimensions without checking for integer overflow, then writes decoded data beyond the undersized allocation. Exploitation requires administrative access to flash a crafted logo and a reboot; successful corruption diverts execution during firmware boot.

The record

CVE
CVE-2023-39539
Published
Dec 6, 2023
Updated
Dec 16, 2025
Vendor
American Megatrends International
Product
Aptio V
Classifications
CWE-434, CWE-20, T1542.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Dec 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 16, 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?

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

  1. Affected versionversion=BKS_5.0 <BKS_5.34

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

American Megatrends International · Aptio Vversion=BKS_5.0 <BKS_5.34

Published CVSS scores

8.2BinarlyCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
7.5AMICVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/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.

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 exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
CWE-20Improper Input Validation
T1542.001Pre-OS Boot: System Firmware

Public exploit references

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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