CVE-2026-12855

Code execution via unvalidated SMM memory boundary

Published Sep 9, 2026 · Updated Sep 9, 2026

Improper input validation in InsydeH2O's H19WMIHandlerSmm allows local users with high privileges to execute arbitrary code. The HP-specific SMM handler fails to validate a memory boundary before operating on attacker-controlled input, but Insyde has not disclosed the exact buffer, request field, or memory operation. Exploitation requires local access and high privileges, and successful code execution crosses the firmware component's security boundary with confidentiality, integrity, and availability consequences.

CVSS severity8.2
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in InsydeH2O's H19WMIHandlerSmm allows local users with high privileges to execute arbitrary code. The HP-specific SMM handler fails to validate a memory boundary before operating on attacker-controlled input, but Insyde has not disclosed the exact buffer, request field, or memory operation. Exploitation requires local access and high privileges, and successful code execution crosses the firmware component's security boundary with confidentiality, integrity, and availability consequences.

The record

CVE
CVE-2026-12855
Published
Sep 9, 2026
Updated
Sep 9, 2026
Vendor
Insyde Software
Product
InsydeH2O UEFI BIOS
Classifications
CWE-20, T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Sep 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=See in the Solution

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Insyde Software · InsydeH2O UEFI BIOSversion=See in the Solution

Published CVSS scores

8.2Insyde SoftwareCVSS: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.

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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

CWE-20Improper Input Validation
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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