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

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

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **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:** Yes
- **Published:** 14 Jan 2026
- **Updated:** 14 Sep 2026
- **Also known as:** BELL-CVE-2025-71142, DEBIAN-CVE-2025-71142, GHSA-v6j2-j656-xqq8, UBUNTU-CVE-2025-71142

## 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: Linux kernel.

## How do I fix CVE-2025-71142?

Apply the vendor's patch.

## Is CVE-2025-71142 being exploited?

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

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-71142 and fix it if it is affected.

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

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-71142/ (Markdown: https://insights.sbomify.com/CVE-2025-71142/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71142
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71142
- OSV: https://osv.dev/vulnerability/CVE-2025-71142

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71142/
Summaries are generated and may contain mistakes; the official description above is the record.