[CVE-2026-72335][MODERATE 7.0] Bluetooth: MGMT: Fix adv monitor add failure cleanup [ Upstream

[CVE-2026-72335][MODERATE 7.0] Bluetooth: MGMT: Fix adv monitor add failure cleanup [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72335
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: MGMT: Fix adv monitor add failure cleanup [ Upstream
Commit: b1a719b3c4359ef731646fb7c7844e53dddbda72
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b1a719b3c4359ef731646fb7c7844e53dddbda72
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72335
Analysis date: Sat, 15 Aug 2026 03:31:36 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A Bluetooth MGMT advertising monitor add failure can free an `adv_monitor` from the MSFT callback while the pending MGMT completion still reads it, causing a confirmed slab-use-after-free and potential local kernel crash.

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

The original Linux kernel CVE announcement for CVE-2026-72335 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72335

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 7.0
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
======================================================================

CVE-2026-72335	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A use-after-free in the Bluetooth MGMT advertising monitor add flow can occur when hci_add_adv_monitor publishes a monitor before the MSFT offload setup is fully completed. If the MSFT add path fails locally or via the callback, the monitor can be freed while mgmt_add_adv_patterns_monitor_complete still uses the original pending command and reads the freed monitor handle. This is a local control plane issue through Bluetooth MGMT commands and is not directly reachable over IP network traffic. For the CVSS the PR:L is used for the paranoid score because a reduced capability local service or delegated Bluetooth management context may be enough in some deployments, although the typical host setup may require CAP_NET_ADMIN. Impact is at least local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact due to a real slab use-after-free, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	REMOTE DANGER INIT UAF NETWORK  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* +1 Memory corruption, weak primitive: confirmed KASAN slab-use-after-free, but the demonstrated stale access is a read of `monitor->handle`, not an attacker-controlled write or callback hijack.
* +1 Real lifetime corruption: ownership of `adv_monitor` is split between the MSFT callback and the pending MGMT completion, allowing one path to free while the other still uses it.
* +1 Reliable kernel crash / strong DoS: KASAN reproduces a slab-use-after-free in `mgmt_add_adv_patterns_monitor_complete()`, and production kernels may crash depending on allocator/debug settings.
* +1 Firmware-mediated external influence: the failure path depends on MSFT offload setup or controller callback errors, not purely on local deterministic logic.
* -1 Privileged/restricted management path: the trigger is through Bluetooth MGMT/control-plane operations, typically mediated by `bluetoothd`, `CAP_NET_ADMIN`, or an equivalent privileged management context.

Paranoid additions/interpretation:

* Treat the confirmed UAF as a stronger memory-corruption triage signal for manual review sensitivity, but cap at 5 because no reclaim, overwrite, type confusion, refcount takeover, or callback control is shown.
* No extra LPE bonus is awarded. Privilege escalation is only a concern from the bug class, not demonstrated by the patch.

Call-site confidence: high. The commit provides the failing call path, allocation path, free path, and the exact completion/callback ownership mismatch.

## 3. Reachability analysis

The bug is triggered locally through Bluetooth MGMT advertising monitor add handling. The allocation path goes through `hci_sock_sendmsg()`, but practical access is normally restricted to privileged Bluetooth management components or users with suitable capabilities. Namespace or container delegation can lower practical privilege in some deployments if Bluetooth management is exposed to a reduced-capability service or container, so PR-like treatment should not assume full host root in every case.

The issue is not directly IP-network reachable. Remote Bluetooth radio traffic alone is not enough based on this patch. Realistic triggering also depends on an MSFT advertising monitor offload capable controller and a failure in the offload add path or callback.

## 4. Severity interpretation

This is more than an ordinary Moderate cleanup because it is a confirmed kernel slab UAF in an async completion path. Realistic demonstrated impact is local DoS or crash. Theoretical memory-corruption risk exists because this is a real freed object access, but the provided evidence does not show attacker-controlled reclaim, write-after-free, function-pointer use, or a reliable LPE primitive.

Overall this should be handled as Actionable Moderate at minimum, not auto-closed. It is not a strong Important candidate unless additional evidence shows controlled reuse or privilege escalation.

## 5. One-sentence report phrase

A Bluetooth MGMT advertising monitor add failure can free an `adv_monitor` from the MSFT callback while the pending MGMT completion still reads it, causing a confirmed slab-use-after-free and potential local kernel crash.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: confirmed UAF plus async ownership mismatch in kernel Bluetooth management code. Even though the demonstrated primitive is limited and typically privileged, this class should receive manual review to confirm whether object reuse or lower-privilege Bluetooth management exposure exists in the target environment.

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

Patch: Bluetooth: MGMT: Fix adv monitor add failure cleanup [ Upstream
Commit: b1a719b3c4359ef731646fb7c7844e53dddbda72
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b1a719b3c4359ef731646fb7c7844e53dddbda72

Changed files:
  net/bluetooth/mgmt.c
  net/bluetooth/msft.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=b1a719b3c4359ef731646fb7c7844e53dddbda72

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

The original Linux kernel CVE announcement for CVE-2026-72335 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72335

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: 3
  Paranoid ActionableScore: 5

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 7.0

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).