[CVE-2026-43023][IMPORTANT] Bluetooth: SCO: fix race conditions in sco_sock_connect() [ Upstream

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

CVE: CVE-2026-43023
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: Bluetooth: SCO: fix race conditions in sco_sock_connect() [ Upstream
Commit: dabf22269242e2f2bf44c43fcdc2fa763df7f9cc
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dabf22269242e2f2bf44c43fcdc2fa763df7f9cc
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43023
Analysis date: Thu, 21 May 2026 00:38:43 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in Bluetooth SCO `connect()` handling can revive a closed and zapped socket, causing double `sock_put()` and use-after-free with local DoS impact and possible higher memory-corruption risk.

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

The original Linux kernel CVE announcement for CVE-2026-43023 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43023

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.

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

CVE-2026-43023	IMPORTANT	CHECK	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-362;*CWE-416;CWE-667;*CWE-672;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A race in Bluetooth SCO connect handling can let two concurrent connect() calls on the same socket pass state checks before the socket lock is held. A disconnect window can let one path close and zap the socket while the other path attaches a new SCO connection and moves the same socket back to BT_CONNECT, leading to a zombie socket, double sock_put, and use-after-free. For the CVSS the PR:L is used because the practical attacker is a local user or process that can operate AF_BLUETOOTH SCO sockets rather than full host root. The issue is local and not directly network reachable over IP, although Bluetooth hardware and an HCI disconnect condition are typically needed. Impact is at least denial of service via kernel crash, and because this is real lifetime corruption in a kernel socket object, worst case confidentiality and integrity impact should remain open for manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	REMOTE OOB LOCK RACE LEAK UAF NETWORK KPANIC 	YES	NO	checked

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

ActionableScore=7
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative score signals:

* Local unprivileged or low-privilege trigger: +1
  The trigger is local use of an AF_BLUETOOTH SCO socket with concurrent `connect()` calls. It does not require remote IP reachability.

* Generic memory corruption, strong corruption primitive: +2
  The commit explicitly describes double `sock_put()` and use-after-free.

* Real lifetime corruption: +1
  The bug is a socket and connection lifetime race where a closed and zapped socket can be revived and later freed incorrectly.

* Reliable kernel crash / strong DoS: +1
  Double `sock_put()` and UAF in a kernel socket object is a credible kernel crash path.

* Availability impact realistic: +1
  The impact can be system-wide kernel instability or crash.

Subtractions:

* Hard or unreliable race / special timing required: -1
  The demonstrated scenario needs two concurrent `connect()` calls plus an HCI disconnect timing window.

Conservative total: 5.

Paranoid additional signals:

* Weak LPE concern: +1
  This is a real UAF in a kernel `struct sock` lifetime path. No controlled reclaim or arbitrary write is shown, but privilege-escalation risk should remain open for manual analysis.

* Broad/common local kernel socket subsystem exposure: +1
  Bluetooth is not universal on servers, but AF_BLUETOOTH is a standard kernel socket family and the bug is reachable through a local socket API when Bluetooth SCO is available.

Paranoid total: 7.

## 3. Reachability analysis

The issue is local, not directly network-reachable over IP. A practical attacker would need the ability to create and operate Bluetooth SCO sockets and trigger concurrent `connect()` calls on the same socket. The strongest demonstrated sequence also involves an HCI disconnect event, so timing and environment matter.

Namespaces and containers may affect exposure depending on whether AF_BLUETOOTH sockets and Bluetooth device access are available inside the container. In typical locked-down containers this is unlikely, but on desktop, embedded, mobile, or Bluetooth-enabled systems a local user may have enough access to exercise the socket path.

The path is not default-exposed on all systems because Bluetooth hardware and SCO support are needed. However, it is not a purely theoretical code path and the commit describes a concrete race confirmed with instrumentation.

## 4. Severity interpretation

This behaves as an actionable Moderate at minimum, with a Strong Important candidate paranoid interpretation. The realistic demonstrated impact is local kernel crash or DoS from double `sock_put()` and UAF. The theoretical higher impact is local privilege escalation through UAF exploitation, but the patch does not show a controlled reclaim primitive, attacker-chosen overwrite, or reliable object-confusion path.

The race requirement and Bluetooth/HCI dependency reduce practical exploitability, but the underlying bug class is real lifetime memory corruption in a kernel socket object, so it should not be auto-closed as a low-risk DoS.

## 5. One-sentence report phrase

A race in Bluetooth SCO `connect()` handling can revive a closed and zapped socket, causing double `sock_put()` and use-after-free with local DoS impact and possible higher memory-corruption risk.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

This is a race-based UAF in a kernel socket lifetime path. Even though exploitation requires local Bluetooth SCO access and careful timing, the memory corruption class and possible LPE concern warrant manual review.

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

Patch: Bluetooth: SCO: fix race conditions in sco_sock_connect() [ Upstream
Commit: dabf22269242e2f2bf44c43fcdc2fa763df7f9cc
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dabf22269242e2f2bf44c43fcdc2fa763df7f9cc

Changed files:
  net/bluetooth/sco.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=dabf22269242e2f2bf44c43fcdc2fa763df7f9cc

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

The original Linux kernel CVE announcement for CVE-2026-43023 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43023

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: 5
  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).