CVE-2023-39283

Local privilege escalation via SMRAM write

Published Nov 2, 2023 · Updated Sep 5, 2024

Memory corruption in CsmInt10HookSmm in InsydeH2O 5.0 through 5.5 allows local users to gain SMM privileges via an SMRAM write. The SMM driver accepts fixed or predictable data and writes it into protected SMRAM, corrupting memory. Exploitation requires local low privileges and no user interaction; successful attacks can compromise confidentiality, integrity, and availability at SMM privilege.

CVSS severity7.8
High
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Memory corruption in CsmInt10HookSmm in InsydeH2O 5.0 through 5.5 allows local users to gain SMM privileges via an SMRAM write. The SMM driver accepts fixed or predictable data and writes it into protected SMRAM, corrupting memory. Exploitation requires local low privileges and no user interaction; successful attacks can compromise confidentiality, integrity, and availability at SMM privilege.

The record

CVE
CVE-2023-39283
Published
Nov 2, 2023
Updated
Sep 5, 2024
Vendor
Insyde Software
Product
InsydeH2O UEFI BIOS
Classifications
CWE-787, T1068
Attack vector
local
Privileges
authenticated

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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=5.0 <=5.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Insyde Software · InsydeH2O UEFI BIOSversion=5.0 <=5.5

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.3Insyde SoftwareCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo