CVE-2026-43133 KVM: nSVM: Always use vmcb01 in VMLOAD/VMSAVE emulation
A flaw in KVM nSVM emulation allows L2 guests to bypass isolation, potentially leading to privilege escalation or code execution on the host.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43133?
CVE-2026-43133 is a high-severity vulnerability in Linux kernel, published on 6 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-43133?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43133?
Apply the vendor's patch.
Is CVE-2026-43133 being exploited?
There is no known exploitation of CVE-2026-43133 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43133, DEBIAN-CVE-2026-43133, GHSA-g9j5-v9rr-m845, ROOT-OS-UBUNTU-2204-CVE-2026-43133, ROOT-OS-UBUNTU-2404-CVE-2026-43133, UBUNTU-CVE-2026-43133.