CVE-2026-64604

Local denial of service via unlocked vmcs12 access

Published Aug 6, 2026 · Updated Aug 6, 2026

Improper locking in Linux KVM allows local users with /dev/kvm access to crash hosts configured to panic on kernel warnings. vmx_update_cr8_intercept() fetches vmcs12 before is_guest_mode() is tested, violating get_vmcs12()'s vCPU-mutex requirement during vCPU creation. The trigger requires KVM access, an in-kernel interrupt controller, unavailable or disabled APICv, lockdep, and panic_on_warn=1; otherwise it emits a warning without memory corruption.

CVSS severity0.0
None
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in Linux KVM allows local users with /dev/kvm access to crash hosts configured to panic on kernel warnings. vmx_update_cr8_intercept() fetches vmcs12 before is_guest_mode() is tested, violating get_vmcs12()'s vCPU-mutex requirement during vCPU creation. The trigger requires KVM access, an in-kernel interrupt controller, unavailable or disabled APICv, lockdep, and panic_on_warn=1; otherwise it emits a warning without memory corruption.

The record

CVE
CVE-2026-64604
Published
Aug 6, 2026
Updated
Aug 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 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?

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

  1. Affected versionversion=3.18
  2. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <258ec63c0f281bf7b50f9de67c8e93b5b7be5ed4
  3. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <3dcfb04dd43b16fa1240fc6487fff578ad57264c
  4. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <570af5db081b87374594a00711ac5760d2ea6844
  5. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <7ef78d71ca713d8c00f7c34ddcf276c808143f77
  6. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <9a21f1defd96c6301c5fb462a78eb51b191bd2dd
  7. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <c7cd3605244c924249dea32632e1bc3e89bda543
  8. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <db8407b9fd06d857a4a5e8bcff1d086d13007711
  9. Affected versionversion=a7c0b07d570848e50fce4d31ac01313484d6b844 <ffaaff82336db84e9b58e7a3e81c2fd64e05ed7a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.18; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <258ec63c0f281bf7b50f9de67c8e93b5b7be5ed4; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <3dcfb04dd43b16fa1240fc6487fff578ad57264c; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <570af5db081b87374594a00711ac5760d2ea6844; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <7ef78d71ca713d8c00f7c34ddcf276c808143f77; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <9a21f1defd96c6301c5fb462a78eb51b191bd2dd; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <c7cd3605244c924249dea32632e1bc3e89bda543; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <db8407b9fd06d857a4a5e8bcff1d086d13007711; version=a7c0b07d570848e50fce4d31ac01313484d6b844 <ffaaff82336db84e9b58e7a3e81c2fd64e05ed7a

Published CVSS scores

0.0OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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