---
id: CVE-2026-93209
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Bluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb

  BT enable fails intermittently with -ETIMEDOUT (-110)
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Bluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb

  BT enable fails intermittently with -ETIMEDOUT (-110).  The kernel log
  shows the HCI Read Local V…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= da77c1d39bc527b31890bfa0405763c82828defb <
    0337fb092873a4146aa854acb554675b49c8f6b5
  - >-
    Linux >= 2af7aa6685e22d0dc546b0d27e5f16d3afe211fa <
    d5eef0747071934a1c080ee617fa4fd3566394c5
  - >-
    Linux >= 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <
    d7723320db4c9cb9ec2b9a36140e6c641dd77814
  - >-
    Linux >= 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <
    d0b28e9655f4b3195210627577f81883dc1d0162
  - >-
    Linux >= 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <
    26f66d5b8a5663af498f7ccc94fc79fb47a2191f
  - >-
    Linux >= 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a <
    f5afdff569a09d1cb8cf19826199d024725576cb
  - Linux 4ff121be63b761950610f422437aaaef8e075c40
  - Linux 18a4c59af609994552c8b39c5438304e070e55c7
  - Linux >= 6.1.83 < 6.1.118
  - Linux >= 6.6.23 < 6.6.157
  - Linux >= 6.7.11 < 6.8
  - Linux >= 6.8.2 < 6.9
  - Linux 6.9
published: '2026-09-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T16:17:15.710'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93209'
references:
  - url: 'https://git.kernel.org/stable/c/0337fb092873a4146aa854acb554675b49c8f6b5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/26f66d5b8a5663af498f7ccc94fc79fb47a2191f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d0b28e9655f4b3195210627577f81883dc1d0162'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d5eef0747071934a1c080ee617fa4fd3566394c5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d7723320db4c9cb9ec2b9a36140e6c641dd77814'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f5afdff569a09d1cb8cf19826199d024725576cb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-24T15:45:56.672Z'
epss: 0.00172
epssPercentile: 0.05878
---

## Overview

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

Bluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb

BT enable fails intermittently with -ETIMEDOUT (-110).  The kernel log
shows the HCI Read Local Version command was sent and the firmware
replied with status 0x00 (logged by hci_req_cmd_complete() BT_DBG),
but the waiter in __hci_cmd_sync_sk() never woke up and timed out
after 10 s:

  bluetooth hci0: Opcode 0xfc00              // __hci_cmd_sync_sk
  bluetooth hci0: opcode 0xfc00 plen 1       // hci_cmd_sync_add
  bluetooth hci0: skb len 4                  // hci_cmd_sync_alloc
  bluetooth hci0: length 1                   // hci_req_sync_run
  Bluetooth: hci0 cmd_cnt 1 cmd queued 1     // hci_cmd_work
  Bluetooth: hci0 type 1 len 4               // hci_send_frame
  Bluetooth: opcode 0xfc00 status 0x00       // hci_req_cmd_complete
  <-- req_skb NULL: req_complete_skb not set,
      hci_cmd_sync_complete() never called,
      req_status stays HCI_REQ_PEND            -->
  <-- 10 s later: wait_event_interruptible_timeout expires -->
  bluetooth hci0: end: err -110              // __hci_cmd_sync_sk

The root cause is that hci_send_cmd_sync() clones the sent command
into hdev->req_skb so that hci_req_cmd_complete() can locate the
registered completion callback.  Under memory pressure this
skb_clone() fails, leaving hdev->req_skb NULL.  The firmware reply
is received and processed, but hci_req_cmd_complete() finds NULL
req_skb, so hci_cmd_sync_complete() is never called, req_status
stays HCI_REQ_PEND, and the waiter times out with -ETIMEDOUT.

req_skb is only used to read bt_cb(skb)->hci callbacks and opcode --
it is never modified.  Replace skb_clone() with skb_get(), which
simply increments the reference count of hdev->sent_cmd without
allocating new memory and therefore cannot fail.

This issue was first observed as a use-after-free in ttyport_close()
when ttyport_open() failed, which was investigated in an earlier
patch series [1].  That investigation led to the discovery of the
true root cause described above.

[1] https://lore.kernel.org/all/20250430111617.1151390-1-quic_cxin@quicinc.com/

## Remediation

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