[CVE-2026-98295][MODERATE REGULAR] Bluetooth: coredump: Quiesce dump work on unregister [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-98295
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: coredump: Quiesce dump work on unregister [ Upstream
Commit: 24af375d7d8aa5f698e4dc41317102f44114351a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=24af375d7d8aa5f698e4dc41317102f44114351a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98295
Analysis date: Sat, 10 Oct 2026 22:41:06 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

======================================================================
ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98295 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98295

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE REGULAR
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-98295	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98295 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=4 LEGACY=MODERATE RESULT=DIFF (independent Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A race in the Bluetooth device coredump lifecycle allows dump_rx or dump_timeout work to remain active while an hci_dev is being unregistered and freed. Disconnecting or unregistering a controller during an active dump can therefore cause asynchronous work or a controller specific producer to access the released hci_dev, resulting in a use after free and at least a kernel crash. For the CVSS the PR:L in the paranoid score accounts for environments where a restricted service, container root, delegated Bluetooth capability, or virtual HCI access can initiate the affected lifecycle without full host administration. AC:H applies because successful triggering depends on winning the timing window between active coredump processing and device teardown. The issue is not directly reachable through ordinary remote Bluetooth traffic based on the supplied code, although a controlled controller or driver specific producer may influence the timing. Impact is at least local denial of service and may include confidentiality, integrity, or privilege escalation impact if the stale hci_dev access can be converted into controlled memory corruption.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3)	MAYBE	REMOTE LOCK DANGER INIT NETWORK SKB DEBUGFS LINUS SYZBOT PACKET  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	-	-	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=3
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 3
* Conservative score: 3
* Raw paranoid score: 3
* Paranoid score: 3
* No floor or cap changed either score.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

Positive signals:

* +2 Real UAF / active lifetime violation. `dump_rx` and `dump_timeout` remain live after `hci_release_dev()` can free `hdev`, allowing asynchronous post-lifetime access.
* +1 Reliable kernel crash / strong DoS. Accessing the freed `hci_dev` can produce a kernel fault, consistent with the syzbot report and the stated UAF mechanics.

Negative signals:

* No negative points. Host-admin privilege, difficult timing, rare hardware, and namespace restrictions are not positively established.

Material non-awarded signals:

* No controlled reclaim, attacker-shaped replacement object, arbitrary write, disclosure, callback control, or LPE is demonstrated.
* Structured stale-object leverage is not awarded. Although `hci_dev` is active and structured, the supplied evidence does not show attacker control over reused storage or security-relevant fields consumed after reuse.
* Attacker-influenced lifetime manipulation is not awarded because one attacker controlling the complete dump-plus-unregister sequence is not established.
* Firmware-mediated influence is not awarded because attacker control of controller firmware or a malicious controller is not established.
* No extra Availability point is awarded for the same crash.
* No race penalty is applied merely because concurrent work and unregister are involved. The evidence does not establish a materially narrow or difficult-to-repeat timing window.
* No privilege penalty is applied because the complete trigger privilege is unresolved.
* B5-R does not apply because no retry-accumulated heap OOB write exists.
* B3-PENDING does not apply because no shared-backing write is established.
* B4-PENDING does not apply because there is no authorization decision or DENY-to-ALLOW transition.

Repeated-release assessment:

* `hci_release_dev()` may end the `hdev` lifetime.
* A stale reference can survive in queued or delayed work.
* No concrete second `put`, `release`, `free`, or refcount mutation on that exact stale reference is shown.
* Concrete repeated release/refcount +1: not awarded.
* Paranoid repeated-refcount leverage +1: not awarded.
* REAL UAF FLOOR 5: not applied because there is no repeated lifetime mutation, controlled reuse, or meaningful post-reuse exploitation surface.

3. Reachability analysis

The complete trigger requires an active Bluetooth devcoredump followed by unregister or disconnect while `dump_rx`, `dump_timeout`, or a producer remains active. Physical disconnect may contribute to teardown, but the evidence does not establish who can reliably initiate the dump and complete the full sequence.

Below-host-admin triggering through virtual HCI, delegated Bluetooth management, a container, or namespace capabilities is not demonstrated. Conversely, host-admin-equivalent privilege is also not positively established because physical removal or controller-driven failure may participate. Therefore both host privilege and namespace scope remain unknown.

Bluetooth hardware is common enough that no rare-hardware penalty applies. The race is associated with teardown, but queued work can remain active after unregister, so the evidence does not justify treating it as an exceptionally hard one-shot race.

4. Primitive and severity interpretation

The exact primitive is an asynchronous post-teardown use-after-free of an active structured `hci_dev`. This is CLASS_B because a real kernel object lifetime violation exists.

The stale use is tied to unregister and coredump shutdown, but it is performed by normal asynchronous coredump work rather than a demonstrated second destructor or refcount operation. The demonstrated consequence is kernel crash or DoS. Memory reuse may theoretically produce stronger effects, but controlled reclaim, meaningful stale-field exploitation, confidentiality impact, integrity impact, and privilege escalation are not established.

ImportantCandidate is NO because this is presently a constrained teardown UAF without concrete reuse, repeated lifetime mutation, disclosure, directed corruption, or security-boundary bypass. AutoDowngradeAllowed is YES because the available evidence supports a crash-oriented CLASS_B issue and does not leave a specific Important-grade exploitation primitive unresolved.

Likely operational severity is ordinary-to-borderline Moderate, with manual confirmation advisable due to the real UAF.

5. One-sentence report phrase

A Bluetooth coredump teardown race can leave asynchronous dump work using a freed hci_dev and cause a local kernel crash, but no controlled reuse, arbitrary write, or privilege-escalation primitive is established.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Confirm whether unprivileged virtual HCI or delegated Bluetooth interfaces can reliably initiate both an active dump and device unregister, and inspect the stale worker operations for any write, callback, or refcount behavior beyond an ordinary fault.

7. Call-site confidence

Call-site confidence: medium

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: Bluetooth: coredump: Quiesce dump work on unregister [ Upstream
Commit: 24af375d7d8aa5f698e4dc41317102f44114351a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=24af375d7d8aa5f698e4dc41317102f44114351a

Changed files:
  include/net/bluetooth/coredump.h
  net/bluetooth/coredump.c
  net/bluetooth/hci_core.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=24af375d7d8aa5f698e4dc41317102f44114351a

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-98295 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98295

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: unknown
  Paranoid ActionableScore: 3

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).