---
id: "CVE-2026-99008"
kind: "vulnerability"
aliases: ["CVE-2026-99008"]
title: "Linux kernel: Bluetooth RFCOMM NULL pointer crash when tty closed"
severity: "unknown"
cvss: null
epss: 0.00209
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["bluetooth", "linux-kernel", "runtime"]
not_affected_if: ["no-bluetooth-rfcomm"]
published_at: "2026-10-23T13:17:23+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99008", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-99008", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel: Bluetooth RFCOMM NULL pointer crash when tty closed

When RFCOMM device registration fails in the Linux kernel Bluetooth stack, the device can still be opened and later closed, which dereferences a NULL pointer and crashes the kernel. The sources describe a kernel oops (general protection fault), and the fix adds a NULL check in rfcomm_dev_shutdown().

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

## How to check

- unknown

## Fix

- Update the Linux kernel to a release that includes the RFCOMM NULL tty_dev check in rfcomm_dev_shutdown() (fixed version not stated in the sources)

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99008
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-99008

## From the sources

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

Bluetooth: RFCOMM: Fix NULL tty_dev dereference in rfcomm_dev_shutdown

syzbot hit a NULL pointer dereference in rfcomm_dev_shutdown() when an
RFCOMM tty is closed.

rfcomm_dev_add() puts the new device on rfcomm_dev_list first and only
then registers the tty device and saves it in dev->tty_dev. If that
registration fails, dev->tty_dev is never set at all. The device can be
looked up in the meantime, so an open() of /dev/rfcommN gets through
rfcomm_tty_install() and attaches to it. When that tty is closed again,
rfcomm_dev_shutdown() uses dev->tty_dev without checking it:

  Oops: general protection fault, probably for non-canonical address
  KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
  RIP: 0010:rfcomm_dev_shutdown+0x48/0xb0 net/bluetooth/rfcomm/tty.c:131
  Call Trace:
   tty_port_shutdown+0x1bf/0x220 drivers/tty/tty_port.c:372
   tty_port_close+0x4e/0x150 drivers/tty/tty_port.c:705
   tty_release+0x359/0x1670 drivers/tty/tty_io.c:1718
   __fput+0x418/0xa50 fs/file_table.c:512

rfcomm_dev_destruct() already copes with a NULL dev->tty_dev. Add the
same check to rfcomm_dev_shutdown(), so the tty device is only moved
when it was actually registered.

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