CVE-2024-58083 KVM: Explicitly verify target vCPU is online in kvm_get_vcpu()
A use-after-free in Linux KVM allows attackers to potentially execute code or escalate privileges by triggering a race condition during vCPU creation.
- 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-2024-58083?
CVE-2024-58083 is a high-severity use after free vulnerability in Linux kernel, published on 6 Mar 2025. 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: Explicitly verify target vCPU is online in kvm_get_vcpu()
Explicitly verify the target vCPU is fully online _prior_ to clamping the index in kvm_get_vcpu(). If the index is "bad", the nospec clamping will generate '0', i.e. KVM will return vCPU0 instead of NULL.
In practice, the bug is unlikely to cause problems, as it will only come into play if userspace or the guest is buggy or misbehaving, e.g. KVM may send interrupts to vCPU0 instead of dropping them on the floor.
However, returning vCPU0 when it shouldn't exist per online_vcpus is problematic now that KVM uses an xarray for the vCPUs array, as KVM needs to insert into the xarray before publishing the vCPU to userspace (see commit c5b077549136 ("KVM: Convert the kvm->vcpus array to a xarray")), i.e. before vCPU creation is guaranteed to succeed.
As a result, incorrectly providing access to vCPU0 will trigger a use-after-free if vCPU0 is dereferenced and kvm_vm_ioctl_create_vcpu() bails out of vCPU creation due to an error and frees vCPU0. Commit afb2acb2e3a3 ("KVM: Fix vcpu_array[0] races") papered over that issue, but in doing so introduced an unsolvable teardown conundrum. Preventing accesses to vCPU0 before it's fully online will allow reverting commit afb2acb2e3a3, without re-introducing the vcpu_array[0] UAF race.
Weakness: CWE-416
Which versions are affected by CVE-2024-58083?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-58083?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2024-58083 being exploited?
There is no known exploitation of CVE-2024-58083 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-59423, BELL-CVE-2024-58083, DEBIAN-CVE-2024-58083, GHSA-gw27-9x3h-33gj, ROOT-OS-UBUNTU-2404-CVE-2024-58083, UBUNTU-CVE-2024-58083.