CVE-2026-64286: KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-25 · updated 2026-10-19
Weakness: CWE-822

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.

Affected products

Linux kernel: from 6.2 before 6.6.145; from 6.7 before 6.12.97; from 6.13 before 6.18.39; from 6.19 before 7.1.4 — fixed in 6.12.97, 6.18.39, 6.6.145, 7.1.4

How to fix

Upgrade to a fixed version: Linux kernel 6.12.97, 6.18.39, 6.6.145, 7.1.4. Check the vendor advisory for mitigations.

References

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