CVE-2026-64172

Guest vCPU hangs via missed AVIC wakeup

Published Jul 19, 2026 · Updated Jul 19, 2026

Denial of service in Linux Kernel KVM allows guest OS users to hang virtual CPUs by triggering faulty AVIC IPI delivery. On affected Hygon Family 18h hosts, AVIC ICR write emulation reads a stale IsRunning bit and omits the failure VM-Exit used to wake a blocking target vCPU. A guest OS user must issue a non-self IPI while AVIC IPI virtualization is enabled; the missed wakeup hangs target vCPUs and delays guest execution indefinitely.

CVSS severityUnavailable
Unscored
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux Kernel KVM allows guest OS users to hang virtual CPUs by triggering faulty AVIC IPI delivery. On affected Hygon Family 18h hosts, AVIC ICR write emulation reads a stale IsRunning bit and omits the failure VM-Exit used to wake a blocking target vCPU. A guest OS user must issue a non-self IPI while AVIC IPI virtualization is enabled; the missed wakeup hangs target vCPUs and delays guest execution indefinitely.

The record

CVE
CVE-2026-64172
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 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=6.17
  2. Affected versionversion=8de4a1c8164e5b2e40d1df764840a31de983f40b <94ade38f317ea086a181db0e6b69c574b3b70a5e
  3. Affected versionversion=8de4a1c8164e5b2e40d1df764840a31de983f40b <9560e6fee887a9594a89fa265b5b9c79b1591803
  4. Affected versionversion=8de4a1c8164e5b2e40d1df764840a31de983f40b <9a12fa5213cfc391e0eed63902d3be98f0913765

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.17; version=8de4a1c8164e5b2e40d1df764840a31de983f40b <94ade38f317ea086a181db0e6b69c574b3b70a5e; version=8de4a1c8164e5b2e40d1df764840a31de983f40b <9560e6fee887a9594a89fa265b5b9c79b1591803; version=8de4a1c8164e5b2e40d1df764840a31de983f40b <9a12fa5213cfc391e0eed63902d3be98f0913765

Published CVSS scores

No CVSS assessment is available in this record.

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

T1499Endpoint Denial of Service

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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