[CVE-2026-80692][MODERATE 7.0] Bluetooth: hci_sync: hold conn in hci_connect_acl/le_sync() callbacks [ Upstream

[CVE-2026-80692][MODERATE 7.0] Bluetooth: hci_sync: hold conn in hci_connect_acl/le_sync() callbacks [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80692
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: Bluetooth: hci_sync: hold conn in hci_connect_acl/le_sync() callbacks [ Upstream
Commit: 9a77f296aff4b2ca5f2928ab3a3220c82d8b4074
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9a77f296aff4b2ca5f2928ab3a3220c82d8b4074
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80692
Analysis date: Fri, 28 Aug 2026 05:17:17 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum**:: Treat as Actionable Moderate at minimum. Strong Important only if manual review confirms attacker-assisted reclaim, reliable stale object reuse, or adjacent Bluetooth triggering without meaningful local privileges.
Manual review required: YES

Summary:
Bluetooth hci_sync queued ACL and LE connection callbacks without holding an hci_conn reference, creating a race where the connection object could be freed while async work still uses it, leading to at least kernel crash and requiring manual review for possible UAF based privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-80692 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80692

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-2026-80692	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:H/I:H/A:H';*CWE-416;CWE-362;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'Bluetooth hci_sync can use an hci_conn pointer after it has been freed because ACL and LE connect callbacks were queued without holding a reference to the connection object. If the connection object is released while the hci_sync task is still running, later callback processing can dereference stale kernel memory and cause at least a kernel crash. For the CVSS the PR:L is used because reliable triggering requires a local user, local process, or Bluetooth management path able to initiate or control the connection flow. The issue is not directly Internet reachable. A nearby Bluetooth peer may influence connection timing only in scenarios where the host initiates or policy triggers a connection, so this should be treated as a manual review point rather than assumed remote reachability. Impact is at least local denial of service and in the paranoid case may include privilege escalation because the primitive is a race based use-after-free in a kernel object lifetime path.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)	YES	REMOTE UAF NETWORK  DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN6 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: Treat as Actionable Moderate at minimum. Strong Important only if manual review confirms attacker-assisted reclaim, reliable stale object reuse, or adjacent Bluetooth triggering without meaningful local privileges.

## 2. Signal breakdown

Conservative signals:

* Local unprivileged or low-privileged trigger: +1. Triggering appears to require a local process or Bluetooth management path able to initiate ACL or LE connection flow.
* Memory corruption, weak primitive: +1. The patch describes a theoretical UAF, but does not show controlled reclaim, overwrite, type confusion, or attacker-selected replacement object.
* Real lifetime corruption: +1. The fix adds hci_conn_get() before queueing async hci_sync work and hci_conn_put() in completion/error paths, which is a real refcount lifetime bug.
* Hard or unreliable race / special timing required: -1. The issue depends on conn being freed while the queued hci_sync task is still running.
* Availability impact realistic: +1. A stale hci_conn dereference can plausibly crash the kernel if the race is hit.

Conservative total: 3

Paranoid additional signals:

* Reliable kernel crash / strong DoS: +1. If the stale pointer is dereferenced after free, a kernel crash is a realistic outcome.
* Weak LPE concern: +1. This is still only weak, because the patch does not demonstrate reclaim or write control, but UAF in a kernel object lifetime path deserves manual review.
* Broad/common client subsystem exposure: +1. Bluetooth is common on desktop, laptop, and mobile systems, although not always enabled on servers.
* Race-UAF cap applied. Conservative score capped below Important. Paranoid score capped at 5 because this is race-dependent UAF without demonstrated controlled reuse or write primitive.

Paranoid total: 5

## 3. Reachability analysis

The most realistic trigger is local: a user process, service, or Bluetooth management path initiates ACL or LE connection handling while the connection object is concurrently released. This should not be treated as Internet-reachable. A nearby Bluetooth peer may influence connection timing, failure, or completion behavior, but the patch does not prove that a peer alone can trigger the bug without host-side initiation or policy support.

Namespaces and containers usually do not expose raw Bluetooth management by default. If a container or reduced-capability service has delegated Bluetooth or network-management access, PR should be treated closer to PR:L rather than PR:H. On ordinary servers without Bluetooth hardware or with Bluetooth disabled, practical exposure is much lower.

## 4. Severity interpretation

This behaves above an ordinary cleanup bug because the patch fixes a real async lifetime/refcounting issue around struct hci_conn. The demonstrated primitive is theoretical race-based UAF with likely DoS impact, not a proven LPE primitive. The conservative interpretation is Borderline Moderate. The paranoid interpretation is Actionable Moderate because kernel UAF lifetime bugs can be underestimated and Bluetooth-adjacent timing should be manually checked.

## 5. One-sentence report phrase

Bluetooth hci_sync queued ACL and LE connection callbacks without holding an hci_conn reference, creating a race where the connection object could be freed while async work still uses it, leading to at least kernel crash and requiring manual review for possible UAF based privilege escalation.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a race-based kernel UAF candidate in an async callback/refcount lifetime path. The patch does not prove LPE, but the object lifetime bug and possible Bluetooth-adjacent timing influence make it unsuitable for automatic closure.

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

Patch: Bluetooth: hci_sync: hold conn in hci_connect_acl/le_sync() callbacks [ Upstream
Commit: 9a77f296aff4b2ca5f2928ab3a3220c82d8b4074
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9a77f296aff4b2ca5f2928ab3a3220c82d8b4074

Changed files:
  net/bluetooth/hci_sync.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=9a77f296aff4b2ca5f2928ab3a3220c82d8b4074

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

The original Linux kernel CVE announcement for CVE-2026-80692 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80692

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: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).