CVE-2026-98972 cgroup/cpuset: Don't access cpuset_cgrp_subsys.root in is_in_v2_mode()
- Exploited in the wild
- Not known
- Fix
- Available
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/[email protected]
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.
Sources
Also known as AZL-110798, BELL-CVE-2026-98972, DEBIAN-CVE-2026-98972, GHSA-pv9v-q67q-mhqc, UBUNTU-CVE-2026-98972.