---
id: "CVE-2026-99015"
kind: "vulnerability"
aliases: ["CVE-2026-99015"]
title: "Linux kernel: Bluetooth HCI socket rebind race crashes the system"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["bluetooth", "kernel", "linux", "runtime"]
not_affected_if: ["bluetooth-disabled"]
published_at: "2026-10-23T13:17:24+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T04:55:44+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99015", "first_seen_at": "2026-10-23T21:57:33+00:00"}]
---

# Linux kernel: Bluetooth HCI socket rebind race crashes the system

Rebinding a Bluetooth HCI socket after its controller is unregistered can race monitor control replay and crash the kernel with a NULL pointer dereference or use-after-free. The sources do not say what an attacker can gain beyond a crash.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- `uname -r` to see the running kernel version
- `grep -i bluetooth /proc/modules` to see whether the Bluetooth stack is loaded
- Compare the kernel version against the fixed release in the upstream commit listed by NVD

## Fix

- Update the Linux kernel to a release that includes the upstream fix (serialization of dead-device detachment in hci_sock, using hci_sk_list.lock for writing)
- Unknown fixed version numbers: the sources do not say

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99015

## From the sources

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

Bluetooth: hci_sock: Serialize dead-device detachment

Rebinding an HCI socket after its controller is unregistered can race
monitor control replay and crash the kernel. hci_sock_bind() clears
hci_pi(sk)->hdev and drops the device reference under only the socket
lock, whereas send_monitor_control_replay() holds hci_sk_list.lock for
reading.

Replay can observe a non-NULL hdev, then bind can clear it and drop the
last reference before create_monitor_ctrl_open() reads hdev->id. This
can cause a NULL pointer dereference if the pointer is reloaded, or a
use-after-free if the old pointer is retained.

The kernel reported:

  KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
  RIP: 0010:create_monitor_ctrl_open+0x579/0x800
  Call Trace:
   hci_sock_bind+0xd96/0x1190
   __sys_bind+0x166/0x200
   __x64_sys_bind+0x6d/0xb0
   do_syscall_64+0xdd/0x4a0
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

The same missing serialization lets hci_send_to_sock() select a socket
for the old device and queue its frame after bind has detached the socket
or installed a new binding.

Take hci_sk_list.lock for writing when clearing the device pointer and
resetting the socket state. This waits for existing replay and delivery
readers to finish before detachment and prevents later readers from
using the old binding. Keep hci_dev_put() outside the critical section
because the final device release can sleep.

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