CVE-2025-71142 cpuset: fix warning when disabling remote partition

Medium 5.5 Published 14 Jan 2026 Updated 14 Sep 2026

A local attacker can trigger a kernel warning and potential instability by manipulating cpuset partitions after offlining CPUs.

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-2025-71142?

CVE-2025-71142 is a medium-severity denial of service vulnerability in Linux kernel, published on 14 Jan 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:

cpuset: fix warning when disabling remote partition

A warning was triggered as follows:

WARNING: kernel/cgroup/cpuset.c:1651 at remote_partition_disable+0xf7/0x110 RIP: 0010:remote_partition_disable+0xf7/0x110 RSP: 0018:ffffc90001947d88 EFLAGS: 00000206 RAX: 0000000000007fff RBX: ffff888103b6e000 RCX: 0000000000006f40 RDX: 0000000000006f00 RSI: ffffc90001947da8 RDI: ffff888103b6e000 RBP: ffff888103b6e000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffff88810b2e2728 R12: ffffc90001947da8 R13: 0000000000000000 R14: ffffc90001947da8 R15: ffff8881081f1c00 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f55c8bbe0b2 CR3: 000000010b14c000 CR4: 00000000000006f0 Call Trace: <TASK> update_prstate+0x2d3/0x580 cpuset_partition_write+0x94/0xf0 kernfs_fop_write_iter+0x147/0x200 vfs_write+0x35d/0x500 ksys_write+0x66/0xe0 do_syscall_64+0x6b/0x390 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f55c8cd4887

Reproduction steps (on a 16-CPU machine):

# cd /sys/fs/cgroup/ # mkdir A1 # echo +cpuset > A1/cgroup.subtree_control # echo "0-14" > A1/cpuset.cpus.exclusive # mkdir A1/A2 # echo "0-14" > A1/A2/cpuset.cpus.exclusive # echo "root" > A1/A2/cpuset.cpus.partition # echo 0 > /sys/devices/system/cpu/cpu15/online # echo member > A1/A2/cpuset.cpus.partition

When CPU 15 is offlined, subpartitions_cpus gets cleared because no CPUs remain available for the top_cpuset, forcing partitions to share CPUs with the top_cpuset. In this scenario, disabling the remote partition triggers a warning stating that effective_xcpus is not a subset of subpartitions_cpus. Partitions should be invalidated in this case to inform users that the partition is now invalid(cpus are shared with top_cpuset).

To fix this issue: 1. Only emit the warning only if subpartitions_cpus is not empty and the effective_xcpus is not a subset of subpartitions_cpus. 2. During the CPU hotplug process, invalidate partitions if subpartitions_cpus is empty.

Which versions are affected by CVE-2025-71142?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-71142?

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-2025-71142 being exploited?

There is no known exploitation of CVE-2025-71142 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2025-71142, DEBIAN-CVE-2025-71142, GHSA-v6j2-j656-xqq8, UBUNTU-CVE-2025-71142.