Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-05-06T00:00:00 kernel: KVM: nSVM: Always use vmcb01 in VMLOAD/VMSAVE emulation 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-372

In the Linux kernel, the following vulnerability has been resolved: KVM: nSVM: Always use vmcb01 in VMLOAD/VMSAVE emulation Commit cc3ed80ae69f ("KVM: nSVM: always use vmcb01 to for vmsave/vmload of guest state") made KVM always use vmcb01 for the fields controlled by VMSAVE/VMLOAD, but it missed updating the VMLOAD/VMSAVE emulation code to always use vmcb01. As a result, if VMSAVE/VMLOAD is executed by an L2 guest and is not intercepted by L1, KVM will mistakenly use vmcb02. Always use vmcb01 instead of the current VMCB.

A flaw was found in the Linux kernel's Kernel-based Virtual Machine (KVM) nSVM module. When a nested virtual machine (L2 guest) executes VMSAVE/VMLOAD instructions, and these are not intercepted by the first-level hypervisor (L1), KVM incorrectly uses `vmcb02` instead of `vmcb01` for managing guest state. This incorrect Virtual Machine Control Block (VMCB) handling could lead to unexpected behavior or state corruption within the virtualized environment.

Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Fix deferred kernel Red Hat Enterprise Linux 8 Fix deferred kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Fix deferred kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-43133 https://nvd.nist.gov/vuln/detail/CVE-2026-43133 https://lore.kernel.org/linux-cve-announce/2026050622-CVE-2026-43133-ffea@gregkh/T