CVE-2026-64434: In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref l2cap_chan_timeout() runs asynchronously and
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref
l2cap_chan_timeout() runs asynchronously and accesses chan->conn. If
the connection is torn down while the timer is running or pending,
chan->conn can be freed, leading to a use-after-free when the timer
worker attempts to lock conn->lock:
| BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]
| BUG: KASAN: slab-use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]
| BUG: KASAN: slab-use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]
| BUG: KASAN: slab-use-after-free in mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318
| Write of size 8 at addr ffff8881298d9550 by task kworker/2:1/83
|
| CPU: 2 UID: 0 PID: 83 Comm: kworker/2:1 Not tainted 7.1.0-rc6-next-20260601-dirty #6 PREEMPT(full)
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
| Workqueue: events l2cap_chan_timeout
| Call Trace:
| <TASK>
| instrument_atomic_read_write include/linux/instrumented.h:112 [inline]
| atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]
| __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]
| mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318
| l2cap_chan_timeout+0x5d/0x1b0 net/bluetooth/l2cap_core.c:422
| process_one_work kernel/workqueue.c:3326 [inline]
| process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409
| worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490
| kthread+0x346/0x430 kernel/kthread.c:436
| ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158
| ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
| </TASK>
|
| Allocated by task 320:
| l2cap_conn_add+0xa7/0x820 net/bluetooth/l2cap_core.c:7075
| l2cap_connect_cfm+0xdb/0xd70 net/bluetooth/l2cap_core.c:7452
| hci_connect_cfm include/net/bluetooth/hci_c
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-64434
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-644340.25% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 16% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-64434 | coverage & exploitation status | NVD · CVE.org |
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