CVE-2026-64284

A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) for x86 systems. This vulnerability occurs when KVM handles fastpath exits, where it may fail to execute vendor-specific cleanup operations before returning control to the virtual machine's userspace. Consequently, memory written by the virtual machine might not be correctly flagged as dirty, leading to the consumption of outdated data. A local attacker with access to a virtual machine could potentially exploit this to cause data integrity issues within the virtualized environment.

This vulnerability is rated as having a Moderate impact because exploitation requires local access within a guest virtual machine and only affects memory dirty-tracking without facilitating host privilege escalation. On Red Hat Enterprise Linux hosts providing x86 hardware virtualization, fastpath exit paths in the KVM hypervisor can bypass vendor exit routines before yielding to userspace, which may prevent modified guest memory from being marked dirty. Environments not utilizing KVM virtualization or running on non-x86 architectures are unaffected.

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.