[CVE-2026-53364][LOW] Bluetooth: hci_conn: Fix memory leak in hci_le_big_terminate()

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

CVE: CVE-2026-53364
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: Bluetooth: hci_conn: Fix memory leak in hci_le_big_terminate()
Commit: e6b78019664dfe37c3dc707f50e7b453d6c7726d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e6b78019664dfe37c3dc707f50e7b453d6c7726d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53364
Analysis date: Mon, 13 Jul 2026 13:55:49 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-53364 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53364

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: LOW
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
======================================================================

CVE-2026-53364	LOW	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'hci_le_big_terminate() can leak an allocated helper object when neither PA sync termination nor BIG sync termination is required and the function returns early. Repeated triggering can accumulate unreleased kernel memory and may eventually cause resource exhaustion and denial of service. For the CVSS the PR:N reflects the paranoid adjacent wireless case where a nearby Bluetooth peer may influence the relevant connection state without local code execution on the victim. The base case is more limited because reliable triggering usually depends on local Bluetooth control plane access. Impact is availability only. There is no UAF, OOB access, arbitrary write, information leak, or supported privilege escalation primitive in this patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)	YES	REMOTE SIMPLEFIX LEAK NETWORK  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2
ActionableScoreLower=1

1. ActionableScore
* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**

2. Signal breakdown
* Adjacent wireless / external influence: +1 paranoid only. A nearby Bluetooth peer may influence PA/BIG sync state, but the patch does not prove reliable remote control of the leak loop.
* Availability impact realistic: +1. Repeated triggering can leak small kernel allocations and may eventually cause resource exhaustion.
* Rare or difficult-to-reach state: -1 conservative. The affected path depends on Bluetooth ISO / BIG / PA sync termination state, not a broad default kernel path.
* No memory corruption signal. This is a missing kfree on an early return, not UAF, OOB, double-free, type confusion, or arbitrary write.
* No LPE signal. No reclaim, stale callback, write primitive, object confusion, or credential/security-boundary bypass is shown.
* Call-site confidence: medium. The patch shows the allocation lifetime and missing free path, but not all external call paths that could force repeated triggering.

3. Reachability analysis
The conservative trigger is local or local-adjacent Bluetooth control/state manipulation, likely requiring a process or Bluetooth stack activity able to create the relevant BIG/PA sync state. A purely unprivileged local trigger is not proven. A paranoid interpretation allows adjacent wireless influence from a nearby Bluetooth peer, but reliable repeated triggering still depends on device state and Bluetooth configuration. The path is not Internet-reachable and is only relevant on systems with Bluetooth and the affected LE Audio / ISO features in use.

4. Severity interpretation
This behaves like an ordinary Moderate / Low-like resource leak. The realistic impact is availability degradation through accumulated memory leakage, not immediate kernel memory corruption. The theoretical worst case is system memory exhaustion after repeated successful triggers, but there is no evidence of privilege escalation, confidentiality impact, integrity impact, or a strong corruption primitive.

5. One-sentence report phrase
A memory leak in hci_le_big_terminate() can occur when no PA or BIG termination is needed, allowing repeated triggering to accumulate unreleased kernel memory and potentially cause a Bluetooth-related resource exhaustion DoS.

6. Manual review recommendation
NO MANUAL CHECK NEEDED
Reason: this is a straightforward memory leak with availability-only impact, no demonstrated memory corruption, no security-boundary bypass, and no plausible LPE primitive from the patch context.

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

Patch: Bluetooth: hci_conn: Fix memory leak in hci_le_big_terminate()
Commit: e6b78019664dfe37c3dc707f50e7b453d6c7726d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e6b78019664dfe37c3dc707f50e7b453d6c7726d

Commit description:

hci_le_big_terminate() allocates iso_list_data via kzalloc_obj but
returns 0 without freeing it when neither pa_sync_term nor big_sync_term
flags are set after evaluating the PA and BIG sync connection state.

This early-return path was introduced when hci_le_big_terminate() was
refactored to take struct hci_conn instead of raw u8 parameters, adding
PA/BIG flag evaluation logic. The existing kfree() on hci_cmd_sync_queue
failure does not cover this path.

Fixes: a7bcffc ("Bluetooth: Add PA_LINK to distinguish BIG sync and PA sync connections")
Cc: stable@vger.kernel.org
Signed-off-by: Pavitra Jha <jhapavitra98@gmail.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/hci_conn.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=e6b78019664dfe37c3dc707f50e7b453d6c7726d

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

The original Linux kernel CVE announcement for CVE-2026-53364 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53364

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:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:N/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: 2

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

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).