---
id: CVE-2026-99011
title: 'Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()

  sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a
  strong reference under hde…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c <
    b108ea7ebba147465f4158d8133f0e8f013762ed
  - >-
    Linux >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c <
    8a98d58f6cfe70d51138cd9ce894e72671d95f8a
  - >-
    Linux >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c <
    816fb1590a4c8cf8d05cd076057616be02e276f0
  - Linux 6.13
published: '2026-10-23'
updated: '2026-10-24'
sourceUpdated: '2026-10-24T14:09:59.382Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-99011'
references:
  - url: 'https://git.kernel.org/stable/c/b108ea7ebba147465f4158d8133f0e8f013762ed'
  - url: 'https://git.kernel.org/stable/c/8a98d58f6cfe70d51138cd9ce894e72671d95f8a'
  - url: 'https://git.kernel.org/stable/c/816fb1590a4c8cf8d05cd076057616be02e276f0'
tags:
  - cve.org
epss: 0.00206
epssPercentile: 0.1016
ingestedAt: '2026-10-23T13:24:55.538Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()

sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a
strong reference under hdev->lock:

    hci_dev_lock(hdev);
    hcon = hci_conn_hash_lookup_handle(hdev, handle);
    ...
    conn = sco_conn_hold_unless_zero(hcon->sco_data);
    hci_dev_unlock(hdev);

but the pointer is cleared from the other side without that lock. When
the last sco_conn reference is dropped, sco_conn_free() ran

    conn->hcon->sco_data = NULL;

with no hdev->lock held, so the RX path could read hcon->sco_data and
call kref_get_unless_zero() on an sco_conn that was concurrently freed:

    BUG: KASAN: slab-use-after-free in sco_conn_hold_unless_zero+0xbe/0x160
    Write of size 4 by task kworker/u17:0
    Workqueue: hci0 hci_rx_work
    Call Trace:
     sco_conn_hold_unless_zero+0xbe/0x160
     sco_recv_scodata+0x13f/0x490
     hci_rx_work+0x3af/0x730

kref_get_unless_zero() only guards against a zero refcount, not against
the backing memory already being freed.

Give hcon->sco_data an actual reference on the sco_conn it points to, so
the object cannot be freed while the pointer is still installed, and only
clear and drop it from sco_conn_del(), which runs under hdev->lock (its
callers, sco_connect_cfm() and sco_disconn_cfm(), hold it). The reader in
sco_recv_scodata() also takes hdev->lock, so the store and the read are
now serialised: the RX path either observes NULL or a reference that is
guaranteed to stay valid until it drops its own.

sco_conn_add() no longer hands its kref_init() reference to the caller as
the connection's only reference; that initial reference is the one owned
by hcon->sco_data, and callers get their own via sco_conn_hold().

Because the sco_conn can now outlive the socket (the association keeps it
alive until the link goes down), the hci_conn can no longer be dropped
from sco_conn_free() without regressing socket close: closing a connected
SCO socket must still tear the link down. Move hci_conn ownership to the
socket instead: __sco_chan_add() takes an hci_conn reference and it is
released from sco_chan_del() and sco_sock_destruct(), exactly once. The
sco_conn no longer owns an hci_conn reference, so sco_conn_add() stops
consuming one and sco_connect() drops the hci_connect_sco() reference on
every path; sco_connect_cfm() no longer needs its hci_conn_hold() dance.

## Affected

- `Linux >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c < b108ea7ebba147465f4158d8133f0e8f013762ed`
- `Linux >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c < 8a98d58f6cfe70d51138cd9ce894e72671d95f8a`
- `Linux >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c < 816fb1590a4c8cf8d05cd076057616be02e276f0`
- `Linux 6.13`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.