CVE-2021-46977 KVM: VMX: Disable preemption when probing user return MSRs
A race condition in KVM VMX allows host MSR corruption if preempted, potentially leading to privilege escalation or code execution.
- 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-2021-46977?
CVE-2021-46977 is a high-severity vulnerability in Linux kernel, published on 28 Feb 2024. 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: VMX: Disable preemption when probing user return MSRs
Disable preemption when probing a user return MSR via RDSMR/WRMSR. If the MSR holds a different value per logical CPU, the WRMSR could corrupt the host's value if KVM is preempted between the RDMSR and WRMSR, and then rescheduled on a different CPU.
Opportunistically land the helper in common x86, SVM will use the helper in a future commit.
Which versions are affected by CVE-2021-46977?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-46977?
Apply the vendor's patch.
Is CVE-2021-46977 being exploited?
There is no known exploitation of CVE-2021-46977 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-46977, GHSA-m99h-2hm4-q649, UBUNTU-CVE-2021-46977.