[CVE-2026-80762][MODERATE 7.0] Bluetooth: hci_sync: Fix accept list UAF during suspend [ Upstream

[CVE-2026-80762][MODERATE 7.0] Bluetooth: hci_sync: Fix accept list UAF during suspend [ Upstream

[AL-KERNEL]

CVE: CVE-2026-80762
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: Bluetooth: hci_sync: Fix accept list UAF during suspend [ Upstream
Commit: bb5f5414d1a6272a16f68684e998f4063dd19f57
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bb5f5414d1a6272a16f68684e998f4063dd19f57
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80762
Analysis date: Fri, 04 Sep 2026 13:42:46 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in the Bluetooth HCI suspend path can leave hci_update_event_filter_sync using an accept-list entry after remove_device has deleted and freed it, causing a kernel use-after-free and likely local DoS, with manual review warranted for possible higher impact in delegated Bluetooth management environments.

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

The original Linux kernel CVE announcement for CVE-2026-80762 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80762

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-2026-80762	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80762 CHECK WITH IMPACT FROM ORIG NN MODERATE	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-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A use-after-free can occur in the Bluetooth HCI suspend path because hci_update_event_filter_sync walks hdev accept_list while synchronous HCI commands may wait for controller responses. During that wait a concurrent remove_device operation can delete and free the current accept list entry, after which the suspend path may read the freed list next pointer and crash in hci_suspend_sync. For the CVSS the PR:L is used for the paranoid score because local Bluetooth management access, a reduced-capability service account, or delegated HCI control may be enough to race accept list updates with suspend handling. The issue is not directly network reachable over IP and normally requires local interaction with HCI or management control paths plus a suspend related execution window. Impact is at least local denial of service via kernel crash and in worst case may allow confidentiality or integrity impact because the primitive is a real kernel use-after-free.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 4)	YES	REMOTE READ DANGER NOMEMCHK UAF NETWORK HARDWARE TEST KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN5	NO	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**::

## 2. Signal breakdown

Conservative signals:

* Memory corruption, weak primitive: +1. The patch and KASAN report show a real slab use-after-free, but only a freed list.next read is demonstrated.
* Real lifetime corruption: +1. The bug is caused by retaining an accept-list node across a controller wait while another path can list_del and kfree it.
* Reliable kernel crash / strong DoS: +1. KASAN reports slab-use-after-free in hci_suspend_sync, and the affected path is kernel workqueue suspend handling.
* Hard or unreliable race / special timing required: -1. Triggering requires an interleaving between suspend event filter update and remove_device.
* Broad/common local subsystem exposure: +1. Bluetooth HCI is common on laptops and many desktop/mobile systems, though not always enabled on servers.

Paranoid additions:

* Local unprivileged or reduced-privilege trigger concern: +1. Full host root is not necessarily required in all practical deployments because Bluetooth management may be reachable through delegated services, desktop components, container root, or reduced-capability accounts.
* Availability impact realistic: +1. The failure occurs in kernel suspend/workqueue code and can produce a host-impacting crash or serious suspend/resume instability.

Not awarded:

* Remote reachable / network-triggerable: +0. This is not an IP-network remote bug.
* Strong LPE plausibility: +0. The patch does not show attacker-controlled reclaim, object replacement, write-after-free, callback control, type confusion, or refcount takeover.
* Confidentiality/integrity impact in conservative score: +0. The demonstrated primitive is a stale list pointer read and crash, not a proven leak or write primitive.

## 3. Reachability analysis

The bug is triggered through local Bluetooth HCI or management control paths combined with a suspend-related execution window. One path walks hdev accept_list in hci_update_event_filter_sync while synchronous HCI commands wait for the controller, and another path removes an accept-list entry through remove_device from hci_sock_sendmsg. Typical systems require privileged Bluetooth management access, often CAP_NET_ADMIN or a privileged Bluetooth service, so the conservative score treats it as not trivially unprivileged. However, practical deployments can delegate Bluetooth operations to desktop services or reduced-capability accounts, so the paranoid score treats PR:L-style reachability as defensible.

Namespaces and containers may matter if HCI control is exposed or delegated into a container or service context, but this is not a normal remote network attack surface. The path is common where Bluetooth is enabled and suspend/resume is used, but the race timing makes exploitation less reliable than a direct parser crash.

Call-site confidence: high. The commit message gives the exact interleaving, allocation path, free path, KASAN report, and the changed code avoids retaining list nodes across controller waits.

## 4. Severity interpretation

This is stronger than an ordinary Moderate cleanup because it is a confirmed kernel UAF in a common subsystem and not merely a warning, leak, or validation-only fix. Realistically, the demonstrated impact is local DoS via kernel crash during Bluetooth suspend handling. Theoretical LPE risk exists only at the manual-review level because UAFs can sometimes become exploitable, but this patch does not show a controlled reclaim or write primitive. Therefore it should be handled as Actionable Moderate at minimum, with Strong Important candidacy only under the paranoid triage model.

## 5. One-sentence report phrase

A race in the Bluetooth HCI suspend path can leave hci_update_event_filter_sync using an accept-list entry after remove_device has deleted and freed it, causing a kernel use-after-free and likely local DoS, with manual review warranted for possible higher impact in delegated Bluetooth management environments.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a real kernel UAF with confirmed KASAN evidence in a common subsystem, and while the demonstrated primitive is mainly crash-oriented, delegated Bluetooth management access and kernel lifetime corruption make auto-closure unsafe.

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

Patch: Bluetooth: hci_sync: Fix accept list UAF during suspend [ Upstream
Commit: bb5f5414d1a6272a16f68684e998f4063dd19f57
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bb5f5414d1a6272a16f68684e998f4063dd19f57

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=bb5f5414d1a6272a16f68684e998f4063dd19f57

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

The original Linux kernel CVE announcement for CVE-2026-80762 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80762

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: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: 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).