[CVE-2026-64470][MODERATE 7.0] Bluetooth: btusb: fix use-after-free on marvell probe failure [ Upstream

[CVE-2026-64470][MODERATE 7.0] Bluetooth: btusb: fix use-after-free on marvell probe failure [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64470
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: Bluetooth: btusb: fix use-after-free on marvell probe failure [ Upstream
Commit: 1edd524de5cc8143ece9c42c466346983dc5b5ed
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1edd524de5cc8143ece9c42c466346983dc5b5ed
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64470
Analysis date: Sat, 25 Jul 2026 14:27:15 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A use-after-free in the Bluetooth btusb probe error path can leave Marvell OOB wakeup TX URBs active after device state is freed, allowing a malicious or faulty USB Bluetooth device to trigger a completion callback on freed memory and potentially crash the kernel.

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

The original Linux kernel CVE announcement for CVE-2026-64470 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64470

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
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CVE-2026-64470	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-404;*CWE-664;Other CVSS 'AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'A use-after-free can occur in the Bluetooth btusb probe error path because TX URBs submitted during Marvell OOB wakeup configuration may remain active after later probe failures free the device state. A completion callback can then run against already released btusb structures, causing a kernel crash and potentially memory corruption. For the CVSS the PR:N is used because no authenticated local account is needed if the attacker can attach or supply a malicious USB Bluetooth device. The vector is physical USB device access rather than network reachable Bluetooth traffic. Impact is at least denial of service via kernel crash. In the paranoid interpretation, the UAF in an asynchronous USB completion path may allow confidentiality and integrity impact and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 5)	YES	OOB USB INIT LEAK UAF  KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* +2 Generic memory corruption: the commit explicitly describes a use-after-free in a TX URB completion callback.
* +1 Real lifetime corruption: the bug is an async lifetime mismatch where URBs can outlive freed btusb probe state.
* +1 Reliable kernel crash / strong DoS: a completion callback using freed state can plausibly crash the kernel.
* +1 Firmware-mediated external influence: a malicious or faulty USB Bluetooth device can influence probe behavior and URB completion timing.
* +1 Privileged kernel/device-management memory corruption path: the corruption occurs in USB/Bluetooth driver probe and URB management code.
* +1 Availability impact realistic: impact is host-kernel availability if the UAF is triggered.
* -2 Physical-only or rare hardware-only condition: practical triggering requires physical USB device influence or equivalent control over the affected Bluetooth USB device path.
* -1 Special timing / probe-failure condition: the vulnerable path requires Marvell OOB wakeup TX URBs plus a later probe failure before cleanup.

Paranoid additional signal:

* +1 Weak LPE concern: the bug is UAF in an asynchronous completion callback, which is stronger than a plain NULL dereference, but there is no demonstrated attacker-controlled reclaim or overwrite primitive. This supports manual review but not a strong LPE score.

## 3. Reachability analysis

The most realistic attacker is someone who can attach, supply, or emulate an affected USB Bluetooth device, especially a Marvell-compatible btusb device that reaches the OOB wakeup configuration path. No authenticated local account is required in the physical-device attack model, but this is not network reachable over Bluetooth traffic or IP networking.

A local user may have limited ability to trigger reprobe or reset behavior only if they have permissions over USB device management, which is usually privileged. Namespaces and containers generally do not make this broadly reachable unless USB device access is deliberately delegated into the container.

The btusb driver is common, but the exact vulnerable path is more specific: Marvell OOB wakeup configuration, submitted TX URBs, and later probe failure before URBs are killed.

## 4. Severity interpretation

This is not an ordinary low-risk cleanup bug because the patch explicitly prevents a use-after-free in an async completion path. Realistically, it behaves primarily as a physical-device-triggered kernel DoS.

Theoretical privilege escalation is not proven. The UAF class and callback context justify paranoid manual review, but the patch does not show attacker-controlled reclaim, controlled overwrite, type confusion, or arbitrary code execution. Therefore it fits Actionable Moderate at minimum, with Strong Important candidate only under a cautious physical-device UAF interpretation.

## 5. One-sentence report phrase

A use-after-free in the Bluetooth btusb probe error path can leave Marvell OOB wakeup TX URBs active after device state is freed, allowing a malicious or faulty USB Bluetooth device to trigger a completion callback on freed memory and potentially crash the kernel.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch explicitly fixes a UAF in an asynchronous USB completion path. Even though exploitation appears physical and hardware-specific, lifetime bugs in completion callbacks can be underestimated and should not be auto-closed.

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

Patch: Bluetooth: btusb: fix use-after-free on marvell probe failure [ Upstream
Commit: 1edd524de5cc8143ece9c42c466346983dc5b5ed
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1edd524de5cc8143ece9c42c466346983dc5b5ed

Changed files:
  drivers/bluetooth/btusb.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=1edd524de5cc8143ece9c42c466346983dc5b5ed

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

The original Linux kernel CVE announcement for CVE-2026-64470 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64470

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:P/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 6.4

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: 4
  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: YES
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).