CVE-2023-53496 x86/platform/uv: Use alternate source for socket to node data
A null dereference in the Linux kernel UV platform code causes system crashes when CPU counts are misconfigured, leading to denial of service.
- 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-2023-53496?
CVE-2023-53496 is a medium-severity vulnerability in Linux kernel, published on 1 Oct 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:
x86/platform/uv: Use alternate source for socket to node data
The UV code attempts to build a set of tables to allow it to do bidirectional socket<=>node lookups.
But when nr_cpus is set to a smaller number than actually present, the cpu_to_node() mapping information for unused CPUs is not available to build_socket_tables(). This results in skipping some nodes or sockets when creating the tables and leaving some -1's for later code to trip. over, causing oopses.
The problem is that the socket<=>node lookups are created by doing a loop over all CPUs, then looking up the CPU's APICID and socket. But if a CPU is not present, there is no way to start this lookup.
Instead of looping over all CPUs, take CPUs out of the equation entirely. Loop over all APICIDs which are mapped to a valid NUMA node. Then just extract the socket-id from the APICID.
This avoid tripping over disabled CPUs.
Which versions are affected by CVE-2023-53496?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53496?
Apply the vendor's patch.
Is CVE-2023-53496 being exploited?
There is no known exploitation of CVE-2023-53496 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-53496, DEBIAN-CVE-2023-53496, GHSA-q4x7-5j3j-pvx9, UBUNTU-CVE-2023-53496.