CVE-2023-30456

Guest crash via unchecked control registers

Published Apr 10, 2023 · Updated Mar 19, 2025

Improper control-register validation in Linux kernel KVM before 6.2.8 allows guest OS users to crash a nested guest. The nested_vmx_check_guest_state function accepts inconsistent VMCS12 CR0 and CR4 values because effective register values can differ when EPT or unrestricted guest mode is disabled. Guest OS users must control an L1 guest running nested VMX on an x86_64 Intel host; the demonstrated consequence is a crash of that guest, not host compromise.

CVSS severity6.5
Medium
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper control-register validation in Linux kernel KVM before 6.2.8 allows guest OS users to crash a nested guest. The nested_vmx_check_guest_state function accepts inconsistent VMCS12 CR0 and CR4 values because effective register values can differ when EPT or unrestricted guest mode is disabled. Guest OS users must control an L1 guest running nested VMX on an x86_64 Intel host; the demonstrated consequence is a crash of that guest, not host compromise.

The record

CVE
CVE-2023-30456
Published
Apr 10, 2023
Updated
Mar 19, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-754, T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Apr 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 19, 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 privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
6.5CISA ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1499.004Application or System Exploitation

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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