[CVE-2026-98632][IMPORTANT] Bluetooth: mgmt: Dequeue pending mesh_send_sync entries on cancel [ Upstream

[CVE-2026-98632][IMPORTANT] Bluetooth: mgmt: Dequeue pending mesh_send_sync entries on cancel [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98632
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: Bluetooth: mgmt: Dequeue pending mesh_send_sync entries on cancel [ Upstream
Commit: f84e52829021d00bca8e067302f597c71af1f71a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f84e52829021d00bca8e067302f597c71af1f71a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98632
Analysis date: Mon, 19 Oct 2026 05:05:56 -0400
ActionableScore: 6
ActionableScore lower bound: 5
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
A locally reachable Bluetooth MGMT cancellation can free a mesh_tx object while queued HCI command work retains and later consumes the same pointer, causing an active-object use after free with kernel-crash and unresolved post-free corruption potential.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-98632 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98632

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: IMPORTANT
Manual review required: YES

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

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-98632	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-98632 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=IMPORTANT (final Legacy and Aegis differ; FINAL: IMPORTANT, 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-672;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A use after free occurs when send_cancel frees a mesh_tx object that is still referenced by a mesh_send_sync entry on hdev cmd_sync_work_list. The later hci_cmd_sync_work execution can pass the freed object to mesh_send_sync or mesh_send_start_complete, potentially causing a kernel crash or further corruption of kernel memory. Triggering requires local access to Bluetooth MGMT mesh send and cancel operations and a timing window between queueing and cancellation. The issue is not directly reachable through Bluetooth radio traffic or another network protocol. For the CVSS the PR:L value is used for the paranoid score because a reduced capability Bluetooth service account, a compromised bluetoothd process, or delegated capabilities may access the management interface without having unrestricted system administration rights. Impact is at least a local denial of service via kernel crash and in the worst case may include confidentiality and integrity impact because the queued worker dereferences a freed kernel object. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 7 and the production ActionableScore returned 6 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to IMPORTANT because the CVSS score, vector or bug class threshold rule was applied. final reconciliation stage IMPORTANT to IMPORTANT because KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were INCREASED_TO_HIGH_BASED_ON_GUESSCVSS and TEMP_KPANIC_MERGE_IMPORTANT_WINS and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 4.1 and ActionableScore 1 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is IMPORTANT.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 6)	MAYBE	REMOTE DEADLOCK UAF NETWORK LINUS INCREASED_TO_HIGH_BASED_ON_GUESSCVSS TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=6
ActionableScoreLower=5
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 5
* Conservative score: 5
* Raw paranoid score: 6
* Paranoid score: 6
* No floor or cap changed either score.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

Conservative positive signals:

* +2 Real UAF. `send_cancel()` calls `mesh_send_complete()` and frees `mesh_tx`, while a queued `mesh_send_sync` entry retains the same raw pointer and later consumes it.
* +1 Reliable kernel crash or strong DoS. Deferred execution of `mesh_send_sync` or `mesh_send_start_complete` with the freed object can realistically produce an invalid dereference, allocator corruption, or kernel fault.
* +1 Attacker-influenced active-object lifetime. The same management client can create a mesh transmission and request cancellation while its asynchronous command remains queued. The transition is repeatable for an actor with access to the relevant MGMT operations.
* +1 Concrete repeated lifetime operation. The first `mesh_send_complete()` can free the object. The exact pointer remains in `cmd_sync_work_list`, and the later error callback contains another `mesh_send_complete()` operation on that pointer.

Paranoid additional signal:

* +1 Structured stale-object exploitation leverage. Before or in addition to the second completion, `mesh_send_sync` actively consumes the stale `mesh_tx` object. The object represents an attacker-supplied mesh transmission rather than fixed passive storage, leaving field consumption and allocator-reuse consequences unresolved.

Important non-awarded signals:

* Controlled reclaim or replacement at the stale address is not demonstrated.
* Arbitrary or directed kernel read or write is not demonstrated.
* Callback target control is not demonstrated. The callback function is fixed, although its data pointer is stale.
* Remote Bluetooth-radio or network reachability is not established.
* No separate confidentiality, integrity, or LPE points are awarded merely because a UAF may theoretically become exploitable.
* No extra Availability point is awarded because it would duplicate the same crash consequence.
* No timing penalty is applied. The vulnerable ordering is driven by queueing followed by cancellation and appears repeatable rather than a proven narrow one-shot race.
* No privilege penalty is applied because the complete capability and user-namespace boundary is unresolved. Unknown privilege is not treated as host-admin privilege.
* B3-PENDING, B4-PENDING, B5-R, and the checksum active-state profiles do not apply.

Repeated lifetime assessment:

* The first release can end lifetime: yes. The commit explicitly says `mesh_send_complete()` frees `mesh_tx`.
* The exact same reference survives: yes. The queued entry retains the raw `mesh_tx` pointer.
* A later lifetime mutation exists: yes on the callback error path, where `mesh_send_start_complete()` invokes `mesh_send_complete()` again.
* Concrete repeated release/refcount +1: awarded.
* Paranoid repeated-refcount bonus: withheld to avoid double-counting. The paranoid point instead covers the distinct active structured processing in `mesh_send_sync`.
* FLOOR 5: applicable in principle, but not applied because the conservative raw score already equals 5.

3. Reachability analysis

The trigger requires local access to Bluetooth MGMT mesh send and cancel operations. It is not directly reachable through received Bluetooth mesh traffic or ordinary network packets.

The supplied evidence does not resolve whether the complete operation requires host root, init-user-namespace capabilities, a privileged `bluetoothd` process, or a reduced and delegated Bluetooth management service. Therefore, `HostAdminRequired` and `RequiresHostUID0` remain `UNKNOWN`.

The complete operation is not shown to work with capabilities obtained in an attacker-created user or network namespace. `NamespaceScopedPrivilege` is consequently `UNKNOWN`, and no local-unprivileged bonus is awarded.

A usable HCI device and Bluetooth Mesh support must exist, and the attacker must be able to submit a mesh transmission and cancel it before the queued synchronous work is consumed. This is prior subsystem availability rather than proof of a separate host-admin setup requirement. The actor controls both management operations, so repeated attempts appear practical. No evidence establishes a materially narrow or externally uncontrollable race.

4. Primitive and severity interpretation

The exact primitive is a post-free use of an active structured `mesh_tx` object by deferred HCI command work. This is not fixed stale DMA storage and not merely passive metadata.

The first `mesh_send_complete()` may destroy and free the object. The queued `cmd_sync_work_list` entry preserves the exact pointer. Later `mesh_send_sync` processes that pointer, and the destroy callback can call `mesh_send_complete()` again on an error, creating a concrete second lifetime operation through potentially freed storage.

This is category B from the repeated-lifetime distinction, not an ordinary cleanup-only stale read. It remains `CLASS_B` because controlled reclaim, refcount takeover, attacker-directed writes, or callback hijacking are not established.

The demonstrated primitive supports a realistic kernel crash and denial of service. Further allocator corruption or privilege escalation is technically possible but unresolved. The active structured use and possible second completion make automatic crash-only downgrading unsafe.

`ImportantCandidate=YES` reflects unresolved Important-versus-Moderate leverage, not proof of Important severity. `AutoDowngradeAllowed=NO` is appropriate because automatic closure would discard a concrete active-object UAF and repeated lifetime operation. The likely operational severity is Actionable Moderate, with mandatory review for possible Important-grade exploitation.

There is no authorization decision bypass, protected-resource access, shared-backing write, retry-accumulated OOB write, or cross-boundary checksum-state corruption in the supplied patch.

5. One-sentence report phrase

A locally reachable Bluetooth MGMT cancellation can free a mesh_tx object while queued HCI command work retains and later consumes the same pointer, causing an active-object use after free with kernel-crash and unresolved post-free corruption potential.

6. Manual review recommendation

MANUAL CHECK REQUIRED

The patch establishes an active structured UAF and a possible second lifetime operation on the same freed object, while reclaim behavior, exact capability scope, and exploitation leverage remain unresolved.

7. Call-site confidence

Call-site confidence: medium

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

Patch: Bluetooth: mgmt: Dequeue pending mesh_send_sync entries on cancel [ Upstream
Commit: f84e52829021d00bca8e067302f597c71af1f71a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f84e52829021d00bca8e067302f597c71af1f71a

Changed files:
  net/bluetooth/mgmt.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=f84e52829021d00bca8e067302f597c71af1f71a

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

The original Linux kernel CVE announcement for CVE-2026-98632 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98632

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:L/I:L/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: 5
  Paranoid ActionableScore: 6

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

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).