CVE-2026-72010

/// Technical description

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

cgroup/cpuset: rebind mm mempolicy to effective_mems, not mems_allowed

Creating a child cpuset where cpuset.mems is never set leads to a div/0

when a VMA mempolicy with MPOL_F_RELATIVE_NODES rebinds in response to a

CPU hotplug event.

Reproduction steps:

1) Create a cgroup w/ cpuset controls (do not set cpuset.mems)

2) Move the task into the child cpuset

3) Create a VMA mempolicy for that task with MPOL_F_RELATIVE_NODES

4) unplug and hotplug a cpu

echo 0 > /sys/devices/system/cpu/cpu1/online

echo 1 > /sys/devices/system/cpu/cpu1/online

5) mempolicy rebind does a div/0 in mpol_relative_nodemask on the

call to __nodes_fold()

The cpuset code passes (cs->mems_allowed) which is not guaranteed to have

nodes to the rebind routine. Use cs->effective_mems instead, which is

guaranteed to have a non-empty nodemask once we reach that code path.

[ david: add a comment, slightly rephrase description ]

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References