---
id: CVE-2026-74509
title: 'Bluetooth: hci_sync: Fix advertising data UAFs'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Bluetooth: hci_sync: Fix advertising data UAFs

  hci_find_adv_instance() returns an adv_info pointer that is valid only
  while hdev->lock is held.  The advertising comman…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f <
    565971488191bf54a87a417abafab6ad0de72201
  - >-
    Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f <
    c4cec575a6d6f7c36808a3a0017b0675968bb06b
  - >-
    Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f <
    95cdcd8c82a501931fd3ae9b3811b0b6da167e94
  - >-
    Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f <
    eb1d8318764de7216e6dbba29a24d69f7ce51348
  - >-
    Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f <
    b16ebdbebd2d37f4cdc590bc3e9db71fe90350a3
  - >-
    Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f <
    cdc36db204ffd97b947d64374cf23a210dc74777
  - Linux 42fe380baaaccbe635c34ca07b29d19b9ec2498d
  - Linux >= 5.15.210 < 5.16
  - Linux 5.17
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:58:37.448836Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:05:51.377Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74509'
references:
  - url: 'https://git.kernel.org/stable/c/565971488191bf54a87a417abafab6ad0de72201'
  - url: 'https://git.kernel.org/stable/c/c4cec575a6d6f7c36808a3a0017b0675968bb06b'
  - url: 'https://git.kernel.org/stable/c/95cdcd8c82a501931fd3ae9b3811b0b6da167e94'
  - url: 'https://git.kernel.org/stable/c/eb1d8318764de7216e6dbba29a24d69f7ce51348'
  - url: 'https://git.kernel.org/stable/c/b16ebdbebd2d37f4cdc590bc3e9db71fe90350a3'
  - url: 'https://git.kernel.org/stable/c/cdc36db204ffd97b947d64374cf23a210dc74777'
tags:
  - cve.org
epss: 0.00249
epssPercentile: 0.15111
ingestedAt: '2026-10-16T19:46:24.352Z'
---

## Overview

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

Bluetooth: hci_sync: Fix advertising data UAFs

hci_find_adv_instance() returns an adv_info pointer that is valid only
while hdev->lock is held.  The advertising command-sync paths perform
instance lookups without that lock and, in some cases, retain the pointer
while waiting for a controller response.

An advertising termination event can therefore interleave as follows:

  hci_cmd_sync_work                 hci_rx_work
  hci_find_adv_instance()
  __hci_cmd_sync_status()
    wait for controller reply       hci_dev_lock()
                                    hci_remove_adv_instance()
                                      kfree(adv)
  adv->scan_rsp_changed = false

KASAN reported:

  BUG: KASAN: slab-use-after-free in hci_set_ext_scan_rsp_data_sync+0x2e1/0x300
  Write of size 1 at addr ffff88810a45d21d by task kworker/u17:0/88
  Workqueue: hci0 hci_cmd_sync_work
  Call Trace:
   hci_set_ext_scan_rsp_data_sync+0x2e1/0x300
   hci_schedule_adv_instance_sync+0x390/0x4c0
   hci_cmd_sync_work+0x173/0x300
  Allocated by task 87:
   hci_add_adv_instance+0x538/0xac0
   add_advertising+0x885/0x1160
  Freed by task 89:
   kfree+0x131/0x3c0
   hci_remove_adv_instance+0x1d8/0x3b0
   hci_le_ext_adv_term_evt+0x17b/0x730

Protect the instance lookup and payload construction in the extended
advertising, scan response, and periodic advertising data paths.  Snapshot
the advertising parameters under hdev->lock, but release the lock before
waiting for the controller.

Clear advertising-data dirty bits before issuing their commands and
restore them after a failure using a fresh lookup.  Likewise, update the
reported transmit power through a fresh lookup after the parameter command
completes.  No adv_info pointer then survives an HCI command wait.

## Affected

- `Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f < 565971488191bf54a87a417abafab6ad0de72201`
- `Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f < c4cec575a6d6f7c36808a3a0017b0675968bb06b`
- `Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f < 95cdcd8c82a501931fd3ae9b3811b0b6da167e94`
- `Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f < eb1d8318764de7216e6dbba29a24d69f7ce51348`
- `Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f < b16ebdbebd2d37f4cdc590bc3e9db71fe90350a3`
- `Linux >= cba6b758711cab946c787f7c15be92cc749b8e1f < cdc36db204ffd97b947d64374cf23a210dc74777`
- `Linux 42fe380baaaccbe635c34ca07b29d19b9ec2498d`
- `Linux >= 5.15.210 < 5.16`
- `Linux 5.17`

## Remediation

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