Medium [CVE-2026-64172] Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)
This medium-severity Red Hat Linux advisory covers CVE-2026-64172 affecting Red Hat Enterprise Linux 10, Red Hat package: kernel.
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Summary
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. 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.
A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) subsystem, specifically affecting Hygon Family 18h processors. Due to an erratum, the hardware may incorrectly read a stale status bit during interrupt processing, preventing the virtual machine from exiting as expected.
This issue can cause KVM to miss critical wakeup signals for virtual CPUs, leading to guest virtual machines becoming unresponsive and experiencing unbounded delays, effectively resulting in a denial of service. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-367. Affected Red Hat products: Red Hat Enterprise Linux 10.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
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