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CVE Record

CVE-2023-52831: cpu/hotplug: Don't offline the last non-isolated CPU

In the Linux kernel, the following vulnerability has been resolved: cpu/hotplug: Don't offline the last non-isolated CPU If a system has isolated CPUs via the "isolcpus=" command line parameter, then an attempt to offline the last housekeeping CPU will result in a WARN_ON() when rebuilding the scheduler domains and a subsequent panic due to and unhandled empty CPU mas in partition_sched_domains_locked(). cpuset_hotplug_workfn() rebuild_sched_domains_locked() ndoms = generate_sched_domains(&doms, &attr); cpumask_and(doms[0], top_cpuset.effective_cpus, housekeeping_cpumask(HK_FLAG_DOMAIN)); Thus results in an empty CPU mask which triggers the warning and then the subsequent crash: WARNING: CPU: 4 PID: 80 at kernel/sched/topology.c:2366 build_sched_domains+0x120c/0x1408 Call trace: build_sched_domains+0x120c/0x1408 partition_sched_domains_locked+0x234/0x880 rebuild_sched_domains_locked+0x37c/0x798 rebuild_sched_domains+0x30/0x58 cpuset_hotplug_workfn+0x2a8/0x930 Unable to handle kernel paging request at virtual address fffe80027ab37080 partition_sched_domains_locked+0x318/0x880 rebuild_sched_domains_locked+0x37c/0x798 Aside of the resulting crash, it does not make any sense to offline the last last housekeeping CPU. Prevent this by masking out the non-housekeeping CPUs when selecting a target CPU for initiating the CPU unplug operation via the work queue.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel flaw can crash a system when CPU isolation is used and the last housekeeping CPU is taken offline. The business impact is availability loss, not data theft, based on the provided sources. It appears most relevant to tuned Linux hosts using isolcpus and CPU hotplug operations.

Executive priority

Prioritize patching for latency-sensitive, virtualized, or appliance-like Linux systems that use CPU isolation. For general Linux fleets without isolcpus or CPU offline operations, urgency is lower but should remain in normal kernel maintenance.

Technical view

With isolcpus configured, CPU hotplug may select an invalid target when offlining the last non-isolated housekeeping CPU. Scheduler domain rebuilding can receive an empty CPU mask, trigger a WARN_ON, then panic in partition_sched_domains_locked. The upstream fix prevents selecting non-housekeeping CPUs for the unplug work queue target.

Likely exposure

Exposure is limited to Linux systems using CPU isolation and CPU hotplug/offline workflows. The source lists Linux kernel affected markers including 6.1.64, 6.5.13, 6.6, 6.6.3, and 6.7, but distro-specific backport status is not provided.

Exploitation context

The bundle does not show active exploitation, public weaponization, or KEV listing. Triggering the crash requires the specific isolated-CPU configuration and an attempt to offline the last housekeeping CPU, which usually implies administrative or operational control.

Researcher notes

The source evidence supports a configuration-dependent kernel denial of service. No CVSS, CWE, exploit evidence, or distro package mapping is included. The fixed behavior masks non-housekeeping CPUs when choosing the CPU unplug work queue target.

Mitigation direction

  • Apply Linux vendor or stable-kernel updates containing the referenced fix.
  • Do not offline the last housekeeping CPU on isolcpus systems until patched.
  • Review operational automation that changes CPU online or offline state.
  • Check distribution advisories for backported kernel package status.

Validation and detection

  • Inventory Linux hosts using CPU isolation or CPU hotplug workflows.
  • Compare running kernel builds with vendor advisories and referenced stable commits.
  • Review boot configuration for isolcpus usage on performance-tuned systems.
  • Confirm operational runbooks preserve at least one housekeeping CPU online.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
5Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxfea9dd8653ff39ce383c54e747bde4c39289b4ad, 07f9e0c9987bf1c4ef57611ad2f789ba68978102, 2b8272ff4a70b866106ae13c36be7ecbef5d5da2, 2b8272ff4a70b866106ae13c36be7ecbef5d5da2, 9734e4c0c470258c32b6aa5ea7ef8a86506c0909unaffected
LinuxLinux6.6, 0, 6.1.64, 6.5.13, 6.6.3, 6.7affected
Weakness

CWE details

No CWE listed

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