CVE-2026-99008 Bluetooth: RFCOMM: Fix NULL tty_dev dereference in rfcomm_dev_shutdown
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99008?
CVE-2026-99008 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
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.
Which versions are affected by CVE-2026-99008?
How do I fix CVE-2026-99008?
Upgrade to a fixed version.
Is CVE-2026-99008 being exploited?
There is no known exploitation of CVE-2026-99008 in the wild and no public exploit code.
Sources
Also known as AZL-110852, BELL-CVE-2026-99008, DEBIAN-CVE-2026-99008, GHSA-5xf6-vj9w-8fx6, UBUNTU-CVE-2026-99008.