CVE-2026-64172

Published Jul 19, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235) Hygon Family 18h CPUs are derived from AMD Family 17h (Zen1) silicon and share the same erratum #1235: hardware may read a stale IsRunning=1 bit during ICR write emulation and silently fail to generate an AVIC_IPI_FAILURE_TARGET_NOT_RUNNING VM-Exit on the sending vCPU. The absence of the VM-Exit causes KVM to miss the required wakeup of blocking target vCPUs, leading to hung vCPUs and unbounded delays in guest execution. Extend the existing AMD Family 17h erratum #1235 workaround to also cover Hygon Family 18h. With IPI virtualization disabled, KVM never sets IsRunning=1 in the Physical ID table, so every non-self IPI generates a VM-Exit and is correctly emulated.

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References

Frequently Asked Questions

What is CVE-2026-64172? +
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235) Hygon Family 18h CPUs are derived from AMD Family 17h (Zen1) silicon and share the same erratum #1235: hardware may read a stale IsRunning=1 bit during ICR write emulation and silently fail to generate an AVIC_IPI_FAILURE_TARGET_NOT_RUNNING VM-Exit on the sending vCPU. The absence of the VM-Exit causes KVM to miss the required wakeup of blocking target vCPUs, leading to hung vCPUs and unbounded delays in guest execution. Extend the existing AMD Family 17h erratum #1235 workaround to also cover Hygon Family 18h. With IPI virtualization disabled, KVM never sets IsRunning=1 in the Physical ID table, so every non-self IPI generates a VM-Exit and is correctly emulated.
How do I check if I'm vulnerable to CVE-2026-64172? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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