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

CVE-2026-98972 is fixed in linux on 1 platform by DEBIAN-CVE-2026-98972 (version 7.2.11-1), released October 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-98972
- Priority: Routine
- CVSS: 4.1 (Moderate)
- EPSS: 0.0016
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 23, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98972

## 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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.11-1 | [DEBIAN-CVE-2026-98972](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98972.md) | Oct 24, 2026 |

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