CVE-2023-54081 xen: speed up grant-table reclaim
A flaw in the Linux kernel's Xen grant-table reclaim mechanism can cause memory leaks and VM freezes, impacting Qubes OS users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-54081?
CVE-2023-54081 is a denial of service vulnerability in Linux, published on 24 Dec 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:
xen: speed up grant-table reclaim
When a grant entry is still in use by the remote domain, Linux must put it on a deferred list. Normally, this list is very short, because the PV network and block protocols expect the backend to unmap the grant first. However, Qubes OS's GUI protocol is subject to the constraints of the X Window System, and as such winds up with the frontend unmapping the window first. As a result, the list can grow very large, resulting in a massive memory leak and eventual VM freeze.
To partially solve this problem, make the number of entries that the VM will attempt to free at each iteration tunable. The default is still 10, but it can be overridden via a module parameter.
This is Cc: stable because (when combined with appropriate userspace changes) it fixes a severe performance and stability problem for Qubes OS users.
Which versions are affected by CVE-2023-54081?
How do I fix CVE-2023-54081?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-54081 being exploited?
There is no known exploitation of CVE-2023-54081 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-54081, DEBIAN-CVE-2023-54081, GHSA-x4pm-f62g-mp4x, ROOT-OS-DEBIAN-11-CVE-2023-54081, ROOT-OS-UBUNTU-2204-CVE-2023-54081, UBUNTU-CVE-2023-54081.