CVE-2026-64286
Received Received - Intake

KVM: arm64 Hyp vCPU Context Flush Vulnerability

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU flush_hyp_vcpu() copies the host vCPU context into the hyp's private vCPU on every run. ctxt_to_vcpu() expects a guest context to have a NULL __hyp_running_vcpu, which is only ever set on the host context, so that it resolves the vCPU via container_of(). While this is generally the case, flush_hyp_vcpu() copies the context verbatim and does not enforce this, so a value provided by the host is dereferenced at EL2 (host -> EL2). Fix by clearing __hyp_running_vcpu after the copy.

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64286
EUVD
EUVD-2026-48998

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a vulnerability in the Linux kernel affecting KVM for arm64 systems. It involves a flaw in the flush_hyp_vcpu() function where the host vCPU context is copied into the hypervisor's private vCPU without clearing the __hyp_running_vcpu pointer. This can lead to improper dereferencing of a host-provided value at EL2, potentially causing security issues.

Detection Guidance

This vulnerability is specific to the Linux kernel's KVM implementation for arm64 systems. Detection requires checking kernel logs for errors related to KVM or hyp mode operations. Commands like dmesg | grep -i kvm or journalctl -k | grep -i kvm may help identify issues. However, no direct detection commands are provided in the context.

Impact Analysis

This vulnerability could allow an attacker with local access to escalate privileges or execute arbitrary code in the hypervisor context. It may lead to denial of service or compromise of guest virtual machines running on affected systems.

Mitigation Strategies

Immediate mitigation involves updating the Linux kernel to a patched version that resolves this issue. Check your distribution's security advisories for kernel updates addressing CVE-2026-64286. If using a custom kernel, apply the patch that clears __hyp_running_vcpu after copying the context.

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