CVE-2022-36337

Firmware code execution via unchecked UEFI variable size

Published Nov 23, 2022 · Updated Apr 25, 2025

Stack buffer overflow in the InsydeH2O MebxConfiguration driver in kernel 5.0 through 5.5 allows local users to execute code in DXE firmware. The vulnerable function calls GetVariable twice for the OS-writable MebxData UEFI variable, then reuses its attacker-controlled size without checking that the one-byte stack destination can hold the returned data. Privileged local access and user interaction are required; overwriting the parent return address enables persistent firmware code execution and NVRAM modification.

CVSS severity7.7
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in the InsydeH2O MebxConfiguration driver in kernel 5.0 through 5.5 allows local users to execute code in DXE firmware. The vulnerable function calls GetVariable twice for the OS-writable MebxData UEFI variable, then reuses its attacker-controlled size without checking that the one-byte stack destination can hold the returned data. Privileged local access and user interaction are required; overwriting the parent return address enables persistent firmware code execution and NVRAM modification.

The record

CVE
CVE-2022-36337
Published
Nov 23, 2022
Updated
Apr 25, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, CWE-121, T1542.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Nov 23, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 25, 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

7.7Insyde SoftwareCVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H
8.2CISA-ADPCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
8.2NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1542.001Pre-OS Boot: System Firmware

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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