[CVE-2026-64405][MODERATE 7.0] Revert "Bluetooth: hci_conn: Consolidate code for aborting connections" This reverts commit 6083089 which is

[CVE-2026-64405][MODERATE 7.0] Revert "Bluetooth: hci_conn: Consolidate code for aborting connections" This reverts commit 6083089 which is

[AL-KERNEL]

CVE: CVE-2026-64405
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Revert "Bluetooth: hci_conn: Consolidate code for aborting connections" This reverts commit 6083089 which is
Commit: 903227b6168bb99fd57d4e3c9c1b5014986198e0
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=903227b6168bb99fd57d4e3c9c1b5014986198e0
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64405
Analysis date: Sat, 25 Jul 2026 05:54:35 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in Bluetooth HCI connection cancellation can dereference a NULL `hdev->sent_cmd` from the receive path during a pending connection request, causing a kernel crash, with additional manual-review concern due to nearby command ownership and `hci_conn` lifetime handling.

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

The original Linux kernel CVE announcement for CVE-2026-64405 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64405

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.

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

CVE-2026-64405	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';**CWE-476;CWE-362;*CWE-416;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'A race in Bluetooth hci_abort_conn() can dereference hdev sent_cmd while it is NULL even though req_status still indicates a pending HCI request. This can be reached from the hci_rx_work receive path during cancellation of a pending connection create command and can cause a general protection fault or kernel crash. For the CVSS the PR:N value is used in the paranoid score because a nearby Bluetooth peer may influence the connection and controller event sequence without a local account on the target, although reliable triggering may still depend on the local Bluetooth stack initiating or aborting a connection. The issue is adjacent network reachable rather than IP network reachable. Impact is at least denial of service. Because the surrounding fix also handles hci_conn lifetime while command status can delete the connection object, limited confidentiality or integrity impact cannot be fully excluded without manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)	YES	REMOTE LOCK DEADLOCK NULLPTR INIT UAF NETWORK SKB HARDWARE DEBUGFS TEST  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	NO	NO	guess

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**

## 2. Signal breakdown

Conservative signals:

* Adjacent network / external Bluetooth influence: +2. The receive path is `hci_rx_work()`, and a nearby Bluetooth peer or controller event sequence can plausibly influence connection completion or rejection timing, but this is not ordinary IP remote reachability.
* Reliable kernel crash / strong DoS: +1. The commit explicitly describes a NULL pointer dereference and general protection fault.
* Broad/common subsystem exposure: +1. Bluetooth is a common kernel subsystem when enabled, although not always active on servers.
* Hard or unreliable race / special timing required: -1. The vulnerable state depends on `req_status == HCI_REQ_PEND` while `hdev->sent_cmd == NULL`.

Paranoid additional signals:

* Weak/indirect corruption candidate: +1. The fix is not only a NULL check. It restructures command ownership and cancellation so an unrelated pending command is not cancelled by mistake.
* Real lifetime corruption concern: +1. The commit explicitly discusses `hci_conn_del()` freeing `conn` while the worker still needs to clear state, and the patch adds `hci_conn_get()` / `hci_conn_put()` to avoid a use-after-free in this lifetime window.

Not counted:

* No strong LPE plausibility. The patch does not show attacker-controlled reclaim, overwrite, callback control, type confusion, or arbitrary write.
* No generic strong memory corruption score. The concrete demonstrated failure is NULL dereference. The UAF concern is lifetime-related but not shown as an exploitable reclaim primitive.
* No separate availability point beyond strong DoS, to avoid double-counting the same crash.

## 3. Reachability analysis

A local process can likely help trigger the path by initiating or aborting Bluetooth connections through normal Bluetooth management flows, but direct low-level management operations are often gated by BlueZ policy or `CAP_NET_ADMIN`. A nearby Bluetooth peer may influence the event sequence by accepting, rejecting, or timing connection procedures, so the paranoid interpretation treats this as adjacent-network reachable with PR:N in CVSS terms.

Namespaces and containers usually do not make this broadly reachable because Bluetooth HCI management is not commonly delegated into untrusted containers. The path is only relevant on systems with Bluetooth hardware and the Bluetooth stack enabled. Realistic exploitation requires a pending create-connection command plus a cancellation or receive-side event race, so timing matters.

Call-site confidence: high. The patch includes the relevant `hci_abort_conn()`, create-connection workers, cancellation helpers, locking, and reference lifetime changes.

## 4. Severity interpretation

This is above an ordinary auto-close Moderate because it is a race in a common wireless subsystem, has adjacent external influence, and the fix touches object lifetime and command ownership semantics. Realistically, the demonstrated impact is kernel crash / DoS from NULL pointer dereference. Theoretical memory-corruption concern exists because the patch explicitly handles a possible `conn` lifetime window, but the patch does not show a practical privilege-escalation primitive.

Overall this fits Actionable Moderate at minimum. It is not a strong Important by default unless additional evidence shows controlled UAF reuse, stale callback use, object replacement, or another concrete escalation primitive.

## 5. One-sentence report phrase

A race in Bluetooth HCI connection cancellation can dereference a NULL `hdev->sent_cmd` from the receive path during a pending connection request, causing a kernel crash, with additional manual-review concern due to nearby command ownership and `hci_conn` lifetime handling.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: adjacent Bluetooth reachability, race timing, reliable crash, and explicit connection-object lifetime handling in the fix make this unsuitable for automatic closure even though the proven primitive is primarily DoS.

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

Patch: Revert "Bluetooth: hci_conn: Consolidate code for aborting connections" This reverts commit 6083089 which is
Commit: 903227b6168bb99fd57d4e3c9c1b5014986198e0
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=903227b6168bb99fd57d4e3c9c1b5014986198e0

Commit description:

It is reported to cause regressions in the 6.1.y tree, so revert it for
now.

Link: https://lore.kernel.org/all/CADRbXaDqx6S+7tzdDPPEpRu9eDLrHQkqoWTTGfKJSRxY=hT5MQ@mail.gmail.com/
Reported-by: Jeremy Lainé <jeremy.laine@m4x.org>
Cc: Salvatore Bonaccorso <carnil@debian.org>
Cc: Mike <user.service2016@gmail.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: Pauli Virtanen <pav@iki.fi>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  include/net/bluetooth/hci_core.h
  net/bluetooth/hci_conn.c
  net/bluetooth/hci_sync.c
  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=903227b6168bb99fd57d4e3c9c1b5014986198e0

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

The original Linux kernel CVE announcement for CVE-2026-64405 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64405

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