{
  "cveId": "CVE-2026-98542",
  "url": "https://patchblox.com/security/cve/CVE-2026-98542",
  "summary": "CVE-2026-98542 is fixed in 20 products on 1 platform, first by DEBIAN-CVE-2026-98542, released October 19, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict",
  "description": "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-\u003Epartition_root_state == PRS_MEMBER and calls remote_partition_enable().  Commit 86888c7bd117 (\u0022cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs\u0022) replaced the cpumask_intersects(tmp-\u003Enew_cpus, subpartitions_cpus) error check in remote_partition_enable() with WARN_ON_ONCE(). 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:    mkdir -p /tmp/cg1   mount -t cgroup2 none /tmp/cg1   echo \u0022\u002Bcpuset\u0022 \u003E /tmp/cg1/cgroup.subtree_control    mkdir /tmp/cg1/A   echo 1 \u003E /tmp/cg1/A/cpuset.cpus   echo 1 \u003E /tmp/cg1/A/cpuset.cpus.exclusive   echo root \u003E /tmp/cg1/A/cpuset.cpus.partition   echo \u0022\u002Bcpuset\u0022 \u003E /tmp/cg1/A/cgroup.subtree_control    mkdir /tmp/cg1/A/B   echo 1 \u003E /tmp/cg1/A/B/cpuset.cpus   echo 1 \u003E /tmp/cg1/A/B/cpuset.cpus.exclusive   echo \u0022\u002Bcpuset\u0022 \u003E /tmp/cg1/A/B/cgroup.subtree_control    mkdir /tmp/cg1/A/B/D   echo 1 \u003E /tmp/cg1/A/B/D/cpuset.cpus   echo 1 \u003E /tmp/cg1/A/B/D/cpuset.cpus.exclusive   echo root \u003E /tmp/cg1/A/B/D/cpuset.cpus.partition  which triggers:    WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable\u002B0x1c1/0x300  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-\u003Enew_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.",
  "published": "2026-10-18T16:17:06Z",
  "severity": "important",
  "epss": 0.00198,
  "epssPercentile": 0.09632,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98542",
  "fixes": [
    {
      "platform": "linux",
      "product": "bpftool6.18",
      "release": "amzn 2023",
      "fixedVersion": "1:6.18.56-125.164.amzn2023",
      "fix": "ALAS2023-2026-3251",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3251",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "product": "bpftool6.18-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1:6.18.56-125.164.amzn2023",
      "fix": "ALAS2023-2026-3251",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3251",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
      "product": "kernel-livepatch-6.18.56-125.164",
      "release": "amzn 2023",
      "fixedVersion": "1:1.0-0.amzn2023",
      "fix": "ALAS2023-2026-3251",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3251",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "release": "amzn 2023",
      "fixedVersion": "1:6.18.56-125.164.amzn2023",
      "fix": "ALAS2023-2026-3251",
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      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "release": "amzn 2023",
      "fixedVersion": "1:6.18.56-125.164.amzn2023",
      "fix": "ALAS2023-2026-3251",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3251",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "product": "kernel6.18-debuginfo-common-aarch64",
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      "fix": "ALAS2023-2026-3251",
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      "released": "2026-11-07T01:06:52Z"
    },
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      "fix": "ALAS2023-2026-3251",
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      "released": "2026-11-07T01:06:52Z"
    },
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      "fix": "ALAS2023-2026-3251",
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      "released": "2026-11-07T01:06:52Z"
    },
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      "fix": "ALAS2023-2026-3251",
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      "fix": "ALAS2023-2026-3251",
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      "released": "2026-11-07T01:06:52Z"
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      "fix": "ALAS2023-2026-3251",
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      "fix": "ALAS2023-2026-3251",
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      "released": "2026-11-07T01:06:52Z"
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      "fix": "ALAS2023-2026-3251",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3251",
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    {
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      "fix": "ALAS2023-2026-3251",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3251",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.9-1",
      "fix": "DEBIAN-CVE-2026-98542",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-98542",
      "released": "2026-10-19T16:27:52Z"
    },
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    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}