---
id: CVE-2025-40308
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Bluetooth: bcsp: receive data only if registered

  Currently, bcsp_recv() can be called even when the BCSP protocol has not
  been registered
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Bluetooth: bcsp: receive data only if registered

  Currently, bcsp_recv() can be called even when the BCSP protocol has not
  been registered. This leads to a NULL pointer…
severity: none
published: '2025-12-08'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T22:10:00.210'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-40308'
references:
  - url: 'https://git.kernel.org/stable/c/164586725b47f9d61912e6bf17dbaffeff11710b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/39a7d40314b6288cfa2d13269275e9247a7a055a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/55c1519fca830f59a10bbf9aa8209c87b06cf7bc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/799cd62cbcc3f12ee04b33ef390ff7d41c37d671'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8b892dbef3887dbe9afdc7176d1a5fd90e1636aa'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b420a4c7f915fc1c94ad1f6ca740acc046d94334'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b65ca9708bfbf47d8b7bd44b7c574bd16798e9c9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ca94b2b036c22556c3a66f1b80f490882deef7a6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00195
epssPercentile: 0.08603
ingestedAt: '2026-10-14T23:00:02.020Z'
---

## Overview

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

Bluetooth: bcsp: receive data only if registered

Currently, bcsp_recv() can be called even when the BCSP protocol has not
been registered. This leads to a NULL pointer dereference, as shown in
the following stack trace:

    KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
    RIP: 0010:bcsp_recv+0x13d/0x1740 drivers/bluetooth/hci_bcsp.c:590
    Call Trace:
     <TASK>
     hci_uart_tty_receive+0x194/0x220 drivers/bluetooth/hci_ldisc.c:627
     tiocsti+0x23c/0x2c0 drivers/tty/tty_io.c:2290
     tty_ioctl+0x626/0xde0 drivers/tty/tty_io.c:2706
     vfs_ioctl fs/ioctl.c:51 [inline]
     __do_sys_ioctl fs/ioctl.c:907 [inline]
     __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
     do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
     do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
     entry_SYSCALL_64_after_hwframe+0x77/0x7f

To prevent this, ensure that the HCI_UART_REGISTERED flag is set before
processing received data. If the protocol is not registered, return
-EUNATCH.

## Remediation

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