[CVE-2026-74510][IMPORTANT] Bluetooth: mgmt: fix UAF in pair command cancellation

[CVE-2026-74510][IMPORTANT] Bluetooth: mgmt: fix UAF in pair command cancellation

[AL-KERNEL]

CVE: CVE-2026-74510
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: Bluetooth: mgmt: fix UAF in pair command cancellation
Commit: 86ed4dd6548ccf277bc691bc912ca06e76b9d80c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=86ed4dd6548ccf277bc691bc912ca06e76b9d80c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74510
Analysis date: Sat, 15 Aug 2026 15:29:42 -0400
ActionableScore: 7
ActionableScore lower bound: 6
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in Bluetooth mgmt pair command cancellation can allow pairing completion or authentication failure callbacks and MGMT_OP_CANCEL_PAIR_DEVICE to free and reuse the same pending command, causing a use-after-free and second list_del with kernel crash risk and possible privilege escalation concern.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-74510 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74510

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: IMPORTANT
Manual review required: YES

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-2026-74510	IMPORTANT	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-415;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A race in Bluetooth mgmt pair command handling can let pairing completion or authentication failure callbacks and MGMT_OP_CANCEL_PAIR_DEVICE operate on the same pending command at the same time. The command can be removed and freed by one path while the other path still dereferences it, which creates a use-after-free and can also lead to a second list_del on the same object. For the CVSS the PR:L is used for the paranoid score because a local user or service able to request pair and cancel operations through Bluetooth management or bluetoothd may be enough in some deployments. The issue is not reachable over IP networking, but a nearby Bluetooth peer may influence pairing completion or failure timing while the local control plane triggers cancellation. Impact is at least local denial of service via kernel crash and in the worst case may allow confidentiality or integrity impact due to kernel memory corruption, so manual review is recommended.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	REMOTE LOCK INIT RACE UAF NETWORK KPANIC 	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=6

## 1. ActionableScore

* Conservative score: 6
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1
  Pairing and cancellation may be reachable by a local user through Bluetooth user workflows or bluetoothd policy, even if direct mgmt socket access is privileged on some systems.

* Privilege escalation plausible, weak LPE concern: +1
  The bug is a UAF involving a freed `mgmt_pending_cmd`, with later dereference and command completion. No controlled reclaim is shown, so this is not a strong LPE primitive by itself.

* Generic memory corruption, strong corruption primitive: +2
  The commit explicitly describes use-after-free and a second `list_del()` on the same object.

* Real lifetime corruption: +1
  The bug is an ownership and lifetime race on `hdev->mgmt_pending`.

* Reliable kernel crash / strong DoS: +1
  UAF plus double list deletion can realistically crash the kernel.

* Broad/common subsystem exposure: +1
  Bluetooth is common on laptops and many desktop systems, though not universal on servers.

Negative signal:

* Hard or unreliable race / special timing required: -1
  The issue requires racing pairing completion or auth failure against cancel pairing.

Paranoid adjustment:

* Stronger LPE plausibility: +1 over conservative
  The stale object is used through command completion paths and list manipulation after free. This is enough to justify manual review as a possible kernel memory corruption escalation candidate, even without a demonstrated reclaim primitive.

## 3. Reachability analysis

The trigger requires local ability to initiate pairing and cancellation operations through the Bluetooth management control plane or a service such as bluetoothd. Direct kernel mgmt access may require privileges such as CAP_NET_ADMIN depending on configuration, but practical desktop policies may expose pair and cancel actions to an unprivileged local user. A nearby Bluetooth peer is not an IP-network attacker, but it can influence pairing completion or authentication failure timing while the local side triggers cancellation.

Namespaces do not automatically make this remotely reachable. Container impact depends on whether Bluetooth devices or management access are delegated into the container. The path is not exposed on systems without Bluetooth hardware, disabled Bluetooth, or no accessible bluetoothd policy.

## 4. Severity interpretation

This is not an ordinary Moderate bookkeeping bug. The patch fixes a real race-based UAF and double list deletion in kernel Bluetooth management state. Realistic exploitation evidence supports at least local DoS, while privilege escalation remains plausible but not demonstrated. Because the stale object can be dereferenced after free and list metadata can be corrupted, this should be treated as an actionable Moderate at minimum and a Strong Important candidate for manual kernel-security review.

## 5. One-sentence report phrase

A race in Bluetooth mgmt pair command cancellation can allow pairing completion or authentication failure callbacks and MGMT_OP_CANCEL_PAIR_DEVICE to free and reuse the same pending command, causing a use-after-free and second list_del with kernel crash risk and possible privilege escalation concern.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch explicitly fixes UAF plus double list deletion in a kernel object lifetime path, and the stale command is dereferenced after possible free. This is memory corruption with plausible LPE concern, even though a practical reclaim or overwrite primitive is not demonstrated.

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

Patch: Bluetooth: mgmt: fix UAF in pair command cancellation
Commit: 86ed4dd6548ccf277bc691bc912ca06e76b9d80c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=86ed4dd6548ccf277bc691bc912ca06e76b9d80c

Commit description:

The pairing completion and authentication failure callbacks look up the
pending MGMT_OP_PAIR_DEVICE command by walking hdev->mgmt_pending. The
lookup returned a command that was still linked on the shared pending list,
without keeping mgmt_pending_lock held for the later dereference and
removal.

A concurrent MGMT_OP_CANCEL_PAIR_DEVICE request can remove and free the
same pending command before the callback uses it. The reverse race is also
possible when cancel_pair_device() gets a command from pending_find() and a
callback removes it before the cancel path dereferences it. This can lead
to a use-after-free and a second list_del().

Make the pairing lookup helpers transfer ownership of the pending command
by removing it from hdev->mgmt_pending while holding mgmt_pending_lock.
The callbacks and cancel path then complete the command and free it
directly, so racing paths cannot find or free the same command again. Take
a temporary hci_conn reference in cancel_pair_device() because the command
completion drops the reference stored in the pending command.

Fixes: e9a416b ("Bluetooth: Add mgmt_pair_device command")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Assisted-by: Codex:gpt-5.4
Signed-off-by: Zihan Xi <xizh2024@lzu.edu.cn>
Reviewed-by: Ren Wei <enjou1224z@gmail.com>
Reported-by: Vega <vega@nebusec.ai>
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/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=86ed4dd6548ccf277bc691bc912ca06e76b9d80c

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

The original Linux kernel CVE announcement for CVE-2026-74510 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74510

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:L/I:L/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: 6
  Paranoid ActionableScore: 7

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).