CVE-2026-98542
In the Linux kernel, the following vulnerability has been resolved:
cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict
When a remote partition is created underneath an existing local partition via a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees parent->partition_root_state == PRS_MEMBER and calls remote_partition_enable().
Commit 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs") replaced the cpumask_intersects(tmp->new_cpus, subpartitions_cpus) error check in remote_partition_enable() with WARN_ON_ONCE().
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As a result, remote_partition_enable() emits a warning and proceeds to enable the remote partition on CPUs that are already owned by the ancestor local partition in subpartitions_cpus.
This can be reproduced on Linux 7.3.0-rc3 with:
which triggers:
and leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions claiming exclusive CPU 1.
Fix this by returning PERR_NOCPUS when tmp->new_cpus intersects subpartitions_cpus in remote_partition_enable(), matching the error code used by remote_cpus_update() for the same subpartitions_cpus conflict, and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh.
Tested in QEMU on Linux 7.3.0-rc3 using the reproducer above and tools/testing/selftests/cgroup/test_cpuset_prs.sh.
Technical details traces, logs and code from the original report
mkdir -p /tmp/cg1 mount -t cgroup2 none /tmp/cg1 echo "+cpuset" > /tmp/cg1/cgroup.subtree_control mkdir /tmp/cg1/A echo 1 > /tmp/cg1/A/cpuset.cpus echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive echo root > /tmp/cg1/A/cpuset.cpus.partition echo "+cpuset" > /tmp/cg1/A/cgroup.subtree_control mkdir /tmp/cg1/A/B echo 1 > /tmp/cg1/A/B/cpuset.cpus echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive echo "+cpuset" > /tmp/cg1/A/B/cgroup.subtree_control mkdir /tmp/cg1/A/B/D echo 1 > /tmp/cg1/A/B/D/cpuset.cpus echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive echo root > /tmp/cg1/A/B/D/cpuset.cpus.partition WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x300
CVSS
NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.20 %
- Percentile among all scored CVEs
- 9
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
References
Raw JSON (NVD)
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{
"id": "CVE-2026-98542",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "86888c7bd117c29eab169c37e5f6bbbf583da983",
"lessThan": "241e67b60308cdce25bba66616a109759edd1d40",
"versionType": "git"
},
{
"status": "affected",
"version": "86888c7bd117c29eab169c37e5f6bbbf583da983",
"lessThan": "0751ab665cb3dcdac224b002565f2e28461740d5",
"versionType": "git"
},
{
"status": "affected",
"version": "86888c7bd117c29eab169c37e5f6bbbf583da983",
"lessThan": "31c88350b7dd1522792f726f79607f31bb55c50f",
"versionType": "git"
}
],
"programFiles": [
"kernel/cgroup/cpuset.c",
"tools/testing/selftests/cgroup/test_cpuset_prs.sh"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.16"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.16",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.18.55",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.9",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/cgroup/cpuset.c",
"tools/testing/selftests/cgroup/test_cpuset_prs.sh"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:06.090",
"references": [
{
"url": "https://git.kernel.org/stable/c/0751ab665cb3dcdac224b002565f2e28461740d5",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/241e67b60308cdce25bba66616a109759edd1d40",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/31c88350b7dd1522792f726f79607f31bb55c50f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict\n\nWhen a remote partition is created underneath an existing local partition\nvia a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees\nparent->partition_root_state == PRS_MEMBER and calls\nremote_partition_enable().\n\nCommit 86888c7bd117 (\"cgroup/cpuset: Add warnings to catch inconsistency\nin exclusive CPUs\") replaced the cpumask_intersects(tmp->new_cpus,\nsubpartitions_cpus) error check in remote_partition_enable() with\nWARN_ON_ONCE(). As a result, remote_partition_enable() emits a warning\nand proceeds to enable the remote partition on CPUs that are already\nowned by the ancestor local partition in subpartitions_cpus.\n\nThis can be reproduced on Linux 7.3.0-rc3 with:\n\n mkdir -p /tmp/cg1\n mount -t cgroup2 none /tmp/cg1\n echo \"+cpuset\" > /tmp/cg1/cgroup.subtree_control\n\n mkdir /tmp/cg1/A\n echo 1 > /tmp/cg1/A/cpuset.cpus\n echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive\n echo root > /tmp/cg1/A/cpuset.cpus.partition\n echo \"+cpuset\" > /tmp/cg1/A/cgroup.subtree_control\n\n mkdir /tmp/cg1/A/B\n echo 1 > /tmp/cg1/A/B/cpuset.cpus\n echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive\n echo \"+cpuset\" > /tmp/cg1/A/B/cgroup.subtree_control\n\n mkdir /tmp/cg1/A/B/D\n echo 1 > /tmp/cg1/A/B/D/cpuset.cpus\n echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive\n echo root > /tmp/cg1/A/B/D/cpuset.cpus.partition\n\nwhich triggers:\n\n WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x300\n\nand leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions\nclaiming exclusive CPU 1.\n\nFix this by returning PERR_NOCPUS when tmp->new_cpus intersects\nsubpartitions_cpus in remote_partition_enable(), matching the error code\nused by remote_cpus_update() for the same subpartitions_cpus conflict, and\nadd a regression test case to\ntools/testing/selftests/cgroup/test_cpuset_prs.sh.\n\nTested in QEMU on Linux 7.3.0-rc3 using the reproducer above and\ntools/testing/selftests/cgroup/test_cpuset_prs.sh."
}
],
"lastModified": "2026-10-19T10:19:10.107",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}