BlackTreeIndependent security intelligence

Full vulnerability report · 2026

CVE-2026-72016High confidence

cpu/hotplug: Fix NULL kobject warning in cpuhp_smt_enable()

Linux · Linux

…UnscoredAssess manually

Recommended action

Needs assessment

No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.

Patch available

Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

13 package states

Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu release	Source package	Vendor state	Fixed version	Evidence
Ubuntu 24.04 LTSnoble · standard archive	`linux-aws-6.14`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-6.11`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-fde-6.14`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-nvidia-6.14`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-gcp-6.11`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-hwe-6.11`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-lowlatency-hwe-6.11`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-nvidia-6.11`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-oem-6.11`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-oracle-6.14`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-raspi-realtime`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-realtime`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-riscv`	Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.	`Not published in this feed`	Canonical record ↗Source updated 4 Sept 2026

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current

CVE-2026-72016 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitykernel: cpu/hotplug: Fix NULL kobject warning in cpuhp_smt_enable()

274 known not affected

The vendor explicitly states that these products are not affected by this CVE.

kernel as a component of Red Hat Enterprise Linux 10
kernel-64k as a component of Red Hat Enterprise Linux 10
kernel-64k-core as a component of Red Hat Enterprise Linux 10
kernel-64k-debug as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-core as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-devel as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-devel-matched as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-modules as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-modules-core as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 10
kernel-64k-devel as a component of Red Hat Enterprise Linux 10
kernel-64k-devel-matched as a component of Red Hat Enterprise Linux 10

Summary: A flaw was found in the Linux kernel's CPU hotplug mechanism on arm64 systems. When a system is booted with more maximum CPUs configured than are physically present, some CPUs are incorrectly marked as present but are not fully registered. This can lead to a kernel warning due to a null kobject dereference during CPU initialization, potentially affecting system stability and hotplug functionality.
Remediation: No remediation text is recorded.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current

ENISA EUVD identifier

EUVD-2026-59115

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state: Present in the current official mapping
Known exploitation: Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score: Not supplied in the stored EUVD record
Advisory evidence: No linked advisory details stored yet

Recommended actionNeeds assessment

No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.

Patch available

What, why and how

In the Linux kernel, the following vulnerability has been resolved: cpu/hotplug: Fix NULL kobject warning in cpuhp_smt_enable() On arm64, when booting with `maxcpus` greater than the number of present CPUs (e.g., QEMU -smp cpus=4,maxcpus=8), some CPUs are marked as 'present' but have not yet been registered via register_cpu(). Consequently, the per-cpu device objects for these CPUs are not yet initialized. In cpuhp_smt_enable(), the code iterates over all present CPUs. Calling _cpu_up() for these unregistered CPUs eventually leads to sysfs_create_group() being called with a NULL kobject (or a kobject without a directory), triggering the following warning in fs/sysfs/group.c: WARNING: fs/sysfs/group.c:137 at internal_create_group+0x41c/0x4bc, CPU#2: sh/181 [...] Call trace: internal_create_group+0x41c/0x4bc (P) sysfs_create_group+0x18/0x24 topology_add_dev+0x1c/0x28 cpuhp_invoke_callback+0x104/0x20c __cpuhp_invoke_callback_range+0x94/0x11c _cpu_up+0x200/0x37c When booting with ACPI, arm64 smp_prepare_cpus() currently sets all enumerated CPUs as "present" regardless of their status in the MADT. This causes issues with SMT hotplug control. For instance, with QEMU's "-smp 4,maxcpus=8" configuration, the MADT GICC entries are populated as follows: 1. The first four CPUs: `Enabled` set but `Online Capable` not set. 2. The remaining four CPUs: `Online Capable` set but `Enabled` not set to support potential hot-plugging. Fix this by: 1. When booting with ACPI, checking the ACPI_MADT_ENABLED flag in the GICC entry before calling set_cpu_present() during SMP initialization. 2. Properly managing the present mask in acpi_map_cpu() and acpi_unmap_cpu() to support actual CPU hotplug events, This aligns with other architectures like x86 and LoongArch. 3. Update the arm64 CPU hotplug documentation to no longer state that all online-capable vCPUs are marked as present by the kernel at boot time. This ensures that only physically available or explicitly enabled CPUs are in the present mask, keeping the SMT control logic consistent with the actual hardware state.

What

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path: the affected interface → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface: Unspecified
Privileges required: Not stated in the selected CVSS metric
User interaction: Not stated in the selected CVSS metric
Attack complexity: Not stated in the selected CVSS metric
Security boundary: Not stated in the selected CVSS metric
Weakness ? CWE means Common Weakness Enumeration.: CWE not yet assigned
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: Not available from the selected scoring authority.
Post-exploitation / living off the land: No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-59115Official EUVD mapping

0 linked advisory records.

Official EUVD record

BSI · German · WID-SEC-W-2026-2852Linux Kernel: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Linux Kernel ausnutzen, um einen Denial of Service herbeizuführen oder einen nicht näher spezifizierten Angriff durchzuführen.

Official advisory

Patch and workaround

Operational remediation based on structured source evidence.

Status ? Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.: Patch available
Affected: eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < ccdf1770a4ba27e31599d24ad970d77a371c7912; eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < 901a489d89ee9c854624c8444090e38e70aed234; eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < f9a82544c7174851f5c7524622f5966dcafd3a47; 6.15
Fixed: < 6.15; 6.18.40 ≤ 6.18.*; 7.1.5 ≤ 7.1.*; 7.2 ≤ *
Action: Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround: No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.

Evidence and provenance

Published 15 Aug 2026 · Last source change 17 Aug 2026, 05:06 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2

CVSS sourceUnavailable

EPSS source

The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.

FIRST · tracked since 2026-08-23

European sourceENISA EUVD · EUVD-2026-59115

Product sourceCNA

Remediation sourceCVE/CNA references

CWE sourceUnavailable

NVD statusNVD received

Missing structured fields: CVSS base score, CWE classification. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates →

17 Aug 2026, 05:06 UTC
Affected versionsThe structured affected or fixed version information changed.
Before
eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < ccdf1770a4ba27e31599d24ad970d77a371c7912; eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < 901a489d89ee9c854624c8444090e38e70aed234; eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < f9a82544c7174851f5c7524622f5966dcafd3a47; 6.15 · Fixed: < 6.15; 6.18.40 ≤ 6.18.*; 7.1.5 ≤ 7.1.*; 7.2-rc3 ≤ *
After
eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < ccdf1770a4ba27e31599d24ad970d77a371c7912; eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < 901a489d89ee9c854624c8444090e38e70aed234; eed4583bcf9a60f8d6dd3a3c7c94dea28134b1eb < f9a82544c7174851f5c7524622f5966dcafd3a47; 6.15 · Fixed: < 6.15; 6.18.40 ≤ 6.18.*; 7.1.5 ≤ 7.1.*; 7.2 ≤ *
CNA ↗
15 Aug 2026, 05:51 UTC
Catalogue recordCVE added to the BlackTree catalogue.
CNA ↗

2026-08-15CVE published

2026-08-17Fixed release or patch reference recorded

ENISA EUVD · EUVD-2026-59115↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗

Technical terms and abbreviations used in this report

CVE: Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS: Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS: Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE: Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA: CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP: Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD: National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT: A computer security incident response team that publishes warnings or coordinates incident response.
PoC: Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF: Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL: Living off the land: abuse of legitimate tools or system functions during an attack.