[CVE-2026-98297][LOW] Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained [ Upstream

[CVE-2026-98297][LOW] Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98297
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained [ Upstream
Commit: ab0678a0701ac4de499428dc1b321659bb74d272
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ab0678a0701ac4de499428dc1b321659bb74d272
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98297
Analysis date: Sat, 10 Oct 2026 23:01:26 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-98297 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98297

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: LOW
Manual review required: NO

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

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

CVE-2026-98297	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98297 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both LOW)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';CWE-362;CWE-367;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '2.5';DESCR 'A race in the Bluetooth HCI transmit path allows hci_send_acl, hci_send_sco, or hci_send_iso to request tx_work while hci_dev_close_sync is draining the device workqueue. The workqueue rejects this request, emits a kernel warning, and drops the transmit work, which can disrupt the affected Bluetooth connection or lose queued transmission progress. For the CVSS the PR:L value is used for the paranoid score because a reduced capability service, container, or delegated process may be able to control the HCI device without having unrestricted root access. Reliable triggering still requires a local Bluetooth socket sender and suitable timing with device shutdown, so AC:H and AV:L apply. The issue is not directly reachable by a remote Bluetooth peer because the demonstrated race also depends on local socket activity and local device close control. The demonstrated impact is limited availability degradation, with no supported UAF, OOB access, information disclosure, privilege escalation, or host wide resource exhaustion.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	MAYBE	REMOTE LOCK DANGER NETWORK HARDWARE LINUS SYZBOT DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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

ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: -1
* Conservative score: 0
* Raw paranoid score: -1
* Paranoid score: 0
* Applied score lower bound: -1 -> 0
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Positive signals:

* +1 Limited availability impact. The race causes `__queue_work()` to reject `tx_work`, emit a warning, and drop transmission work, potentially disrupting the affected Bluetooth connection.
* No reliable kernel-crash point was awarded. The demonstrated result is a warning and dropped work, not panic or host-wide failure.

Negative signals:

* -2 Host-admin-equivalent operation. The demonstrated race uses `HCIDEVDOWN`, which requires control over the host HCI device through host `CAP_NET_ADMIN` or equivalent authority.

Important non-awarded signals:

* No UAF, OOB access, refcount corruption, double release, or stale post-lifetime access is established.
* No arbitrary or constrained kernel-memory write is established.
* No controlled reclaim, structured stale-object leverage, disclosure, authorization bypass, or privilege escalation is established.
* No remote-reachability point was awarded. A remote Bluetooth peer does not control the complete socket-write plus `HCIDEVDOWN` sequence.
* No race penalty was applied merely because this is a race. The supplied evidence does not establish unusually narrow or uncontrollable timing.
* No additional availability point was awarded because persistent or host-wide unavailability is not demonstrated.
* NEW52 B5-R does not apply because there is no heap OOB write.
* NEW53 B3-PENDING does not apply because there is no shared-backing write.
* NEW54 B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW.

3. Reachability analysis

The transmit side is reachable through local L2CAP, SCO, or ISO socket writes. The competing operation is `hci_dev_close_sync()` during `HCIDEVDOWN`, which controls a host HCI device and is privilege-gated by host-level network-administration authority.

An ordinary socket user can exercise only the send side. The supplied evidence does not show that such a user can independently initiate the required device-down transition. Combining an unprivileged sender with an unrelated administrator performing `HCIDEVDOWN` does not establish a complete attacker-controlled trigger.

Numeric host UID 0 is not inherently required because the relevant authority may be represented by host `CAP_NET_ADMIN`. This is nevertheless host-admin-equivalent control over a host-owned physical HCI device. The complete operation is not established as available through an attacker-created user or network namespace.

A Bluetooth HCI device and active socket are prerequisites, but no rare-hardware penalty is applied. Repeated socket writes may increase the chance of meeting the close transition, but the attacker still needs control of, or coincidence with, the privileged device shutdown.

4. Primitive and severity interpretation

The exact primitive is an invalid workqueue scheduling attempt after the workqueue has entered its draining state. `__queue_work()` detects `__WQ_DRAINING`, emits a warning, and refuses the work.

This is neither active structured-object UAF nor fixed stale storage. No object is shown to have ended its lifetime before use. There is no repeated release or refcount mutation.

The demonstrated consequence is dropped Bluetooth transmit work and possible connection-level availability degradation. A kernel crash, memory corruption, persistent resource leak, host-wide denial of service, confidentiality impact, integrity impact, and privilege escalation are unsupported.

The issue is therefore CLASS_C rather than CLASS_A or CLASS_B. `ImportantCandidate=NO` because no Important-preserving primitive exists. `AutoDowngradeAllowed=YES` because the behavior is constrained, privilege-gated, and limited to WARN plus dropped work.

5. One-sentence report phrase

A privileged HCI device shutdown racing with a local Bluetooth socket write can attempt to queue transmit work onto a draining workqueue, causing a kernel warning and dropped transmission work without demonstrated memory corruption or host-wide failure.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes only a guarded workqueue-state race with limited availability impact and no unresolved corruption, lifetime, authorization, or security-boundary primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained [ Upstream
Commit: ab0678a0701ac4de499428dc1b321659bb74d272
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ab0678a0701ac4de499428dc1b321659bb74d272

Changed files:
  kernel/workqueue.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=ab0678a0701ac4de499428dc1b321659bb74d272

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

The original Linux kernel CVE announcement for CVE-2026-98297 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98297

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 2.5

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: 0

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).