[CVE-2026-64178][MODERATE REGULAR] Bluetooth: bnep: Fix UAF read of dev->name

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

CVE: CVE-2026-64178
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: bnep: Fix UAF read of dev->name
Commit: a75bbcb10cb21acc169b785e9804f57d97873a9c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a75bbcb10cb21acc169b785e9804f57d97873a9c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64178
Analysis date: Sun, 19 Jul 2026 16:08:30 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline manual-review Moderate, not an Important candidate
Manual review required: NO

Summary:
Bluetooth BNEP can read `net_device->name` after the device is freed during a tight concurrent connection teardown race, causing a local CAP_NET_ADMIN-gated UAF read with mainly DoS-level practical impact.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64178 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64178

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: NO

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-2026-64178	MODERATE	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '5.3';DESCR 'A use-after-free read in Bluetooth BNEP can occur because bnep_add_connection() dropped bnep_session_sem before copying dev name into the connection request. A concurrent bnep_del_connection() can cause the bnep_session() thread to tear down and free the net_device during this tight race window, so the later name copy reads from freed memory. For the CVSS the PR:L is used for the paranoid score because CAP_NET_ADMIN may be delegated to a container root or service account in some deployments, although the base case is PR:H for normal administrative network management. The issue is local and control-plane triggered, not directly network reachable through Bluetooth traffic alone. Impact is primarily local denial of service and at most a limited information exposure risk from a stale name read, with no supported write primitive or direct privilege escalation path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual-review Moderate, not an Important candidate (with actual score 2)	YES	REMOTE RACE UAF NETWORK  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline manual-review Moderate, not an Important candidate**

## 2. Signal breakdown

Conservative signals:

* Memory corruption, weak primitive: +1. This is a race-dependent UAF read of `dev->name`, not a demonstrated write-after-free, callback hijack, refcount takeover, or controlled object replacement.
* Real lifetime corruption: +1. The freed object is a `net_device` that can be released by the concurrent BNEP session teardown path.
* Hard or unreliable race: -1. The commit explicitly says this requires fully tearing down a netdev during a tight race window.
* Requires CAP_NET_ADMIN in typical deployments: -2. `bnep_add_connection()` requires passing a `capable(CAP_NET_ADMIN)` check.
* Availability impact: +1 at most. A kernel crash is plausible in debug or unlucky memory-reuse cases, but the patch mainly shows a stale read, not a reliable system-wide DoS primitive.

Paranoid adjustment:

* Treat CAP_NET_ADMIN as reduced-privilege in container or service-account deployments rather than full host-root: effective penalty reduced.
* Keep the Race-UAF downgrade rule: no LPE bonus, no confidentiality bonus, no integrity bonus, because the patch does not show controlled reclaim, stale object replacement, writable stale access, type confusion, callback dispatch, or refcount abuse.

## 3. Reachability analysis

The bug is local and control-plane triggered. It is not directly network reachable through Bluetooth traffic alone. A realistic trigger requires a caller able to create a BNEP connection and a concurrent deletion path that tears down the associated netdev while `bnep_add_connection()` is copying `dev->name`.

In normal deployments this requires CAP_NET_ADMIN, so the conservative interpretation is privileged local access. In containerized or delegated-network-management environments, CAP_NET_ADMIN may be held by a reduced-privilege root or service account, which supports the paranoid score but still does not make the bug unprivileged.

Bluetooth BNEP is also not a broad default server-side attack surface.

## 4. Severity interpretation

This behaves like a low-end Moderate or borderline manual-review issue, not an Important-class vulnerability. Theoretical memory lifetime corruption exists because this is a UAF read, but realistic exploitation evidence is weak. The stale access is read-only, the race window is tight, and there is no demonstrated attacker-controlled reclaim, write primitive, type confusion, or privilege-escalation path.

The issue should not be auto-upgraded solely because it is a UAF. It also should not be fully auto-closed without human review, because race-based lifetime bugs can be subtle and the affected object is a kernel networking object.

## 5. One-sentence report phrase

Bluetooth BNEP can read `net_device->name` after the device is freed during a tight concurrent connection teardown race, causing a local CAP_NET_ADMIN-gated UAF read with mainly DoS-level practical impact.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is a real race-based UAF read, but the primitive is weak, local, CAP_NET_ADMIN-gated, and does not show controlled reuse, write access, or a credible LPE path.

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

Patch: Bluetooth: bnep: Fix UAF read of dev->name
Commit: a75bbcb10cb21acc169b785e9804f57d97873a9c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a75bbcb10cb21acc169b785e9804f57d97873a9c

Commit description:

bnep_add_connection() needs to keep holding the bnep_session_sem while
reading dev->name (just like bnep_get_connlist() does); otherwise the
bnep_session() thread can concurrently free the net_device, which can for
example be triggered by a concurrent bnep_del_connection().

(This UAF is fairly uninteresting from a security perspective;
calling bnep_add_connection() requires passing a capable(CAP_NET_ADMIN)
check. It also requires completely tearing down a netdev during a fairly
tight race window.)

Cc: stable@vger.kernel.org
Fixes: 1da177e ("Linux-2.6.12-rc2")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/bluetooth/bnep/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=a75bbcb10cb21acc169b785e9804f57d97873a9c

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

The original Linux kernel CVE announcement for CVE-2026-64178 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64178

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:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 5.3

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: 1
  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).