# CVE-2026-98972: cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** AZL-110798, BELL-CVE-2026-98972, DEBIAN-CVE-2026-98972, GHSA-pv9v-q67q-mhqc, UBUNTU-CVE-2026-98972

## What is CVE-2026-98972?

CVE-2026-98972 is a vulnerability in Linux, published on 23 Oct 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()

After seeing the patch [1] to guard is_in_v2_mode() with RCU, it makes
me realize that is_in_v2_mode() may be called in a context where a new
cgroup filesystem is being rebound with stale cpuset_cgrp_subsys.root
pointer. Avoid this potential UaF situation by adding a new cpuset_v2_mode
flag which is set when the cpuset_v2_mode mount option is used. This
flag is written into only when cpuset_bind() is being called with a
stable cpuset_cgrp_subsys.root value. The is_in_v2_mode() helper is
modified to read the new cpuset_v2_mode flag instead of accessing
cpuset_cgrp_subsys.root directly.

[1] https://lore.kernel.org/lkml/20260929084124.626693-2-arighi@nvidia.com

## Which versions are affected by CVE-2026-98972?


## How do I fix CVE-2026-98972?

Upgrade to a fixed version.

## Is CVE-2026-98972 being exploited?

There is no known exploitation of CVE-2026-98972 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98972 and fix it if it is affected.

What it is: CVE-2026-98972 is a vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-98972 in the wild and no public exploit code.

Affected product: Linux. 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-2026-98972/ (Markdown: https://insights.sbomify.com/CVE-2026-98972/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98972
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98972
- OSV: https://osv.dev/vulnerability/CVE-2026-98972

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98972/
Summaries are generated and may contain mistakes; the official description above is the record.