CVE-2026-64247

A flaw was found in the Linux kernel's KVM (Kernel-based Virtual Machine) Hyper-V component. A local attacker with access to a KVM guest could exploit this by providing an out-of-range Virtual Processor (VP) ID during a paravirtual Translation Lookaside Buffer (TLB) flush. This could lead to an out-of-bounds read in the host kernel, potentially causing a denial of service (DoS) due to a kernel crash or warning. Limited information disclosure or integrity impact may also be possible.

This vulnerability is rated as Moderate severity because triggering the flaw requires an authenticated user within a guest virtual machine configured with nested virtualization and Hyper-V hypercall emulation. In typical Red Hat Enterprise Linux host environments, virtual machines do not expose enlightened VMCS and Hyper-V paravirtualization features unless explicitly provisioned for nested Hyper-V workloads. Successful exploitation is confined to an out-of-bounds memory read on the hypervisor host, which can induce a host kernel crash resulting in denial of service, with limited risk of leaking host memory.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.