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 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_core.h:2139 [inline] | hci_remote_features_evt+0x52f/0x9f0 net/bluetooth/hci_event.c:3760 | hci_event_func net/bluetooth/hci_event.c:7796 [inline] | hci_event_packet+0x561/0xa70 net/bluetooth/hci_event.c:7847 | hci_rx_work+0x370/0x890 net/bluetooth/hci_core.c:4040 | 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 | | Freed by task 322: | hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline] | hci_conn_hash_flush+0x101/0x1f0 net/bluetooth/hci_conn.c:2736 | hci_dev_close_sync+0x889/0xde0 net/bluetooth/hci_sync.c:5405 | hci_dev_do_close net/bluetooth/hci_core.c:502 [inline] | hci_unregister_dev+0x1f7/0x370 net/bluetooth/hci_core.c:2679 | vhci_release+0x12a/0x180 drivers/bluetooth/hci_vhci.c:690 | __fput+0x369/0x890 fs/file_table.c:510 | task_work_run+0x160/0x1d0 kernel/task_work.c:233 | get_signal+0xf5b/0x1120 kernel/signal.c:2810 | arch_do_signal_or_restart+0x4d/0x600 arch/x86/kernel/signal.c:337 | __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] | exit_to_user_mode_loop+0x85/0x510 kernel/entry/common.c:98 | do_syscall_64+0x263/0x3d0 arch/x86/entry/syscall_64.c:100 | entry_SYSCALL_64_after_hwframe+0x77/0x7f | | The buggy address belongs to the object at ffff8881298d9400 | which belongs to the cache kmalloc-512 of size 512 | The buggy address is located 336 bytes inside of | freed 512-byte region [ffff8881298d9400, ffff8881298d9600)
Leer descripción completaMostrar menos
Fix it by having chan->conn hold a reference to l2cap_conn (via l2cap_conn_get) when the channel is added to the connection, and releasing it in the channel destructor. This ensures the l2cap_conn remains alive as long as the channel exists.
A new FLAG_DEL channel flag is introduced to indicate that the ch ---truncated---
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 8.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.26%
- Percentil entre todas las CVEs puntuadas: 16
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1210Exploitation of Remote Serviceslateral movement45 % - Impacto principal
T1068Exploitation for Privilege Escalationprivilege escalation65 %
Vulnerabilidad local de use-after-free (CWE-416) en subsistema Bluetooth del kernel Linux. Requiere acceso de red adyacente (AV:A) para exploit; UAF puede permitir escalada de privilegios o DoS. El vector CVSS y CWE no describen ejecución remota de comandos.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- CWE-416
Referencias
- https://git.kernel.org/stable/c/0b0e2bf39cf99e458d991b9df253727e036a7d7d
- https://git.kernel.org/stable/c/32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b
- https://git.kernel.org/stable/c/50c38d9f42a529691e4e67ea9cedf4f0bfc8d277
- https://git.kernel.org/stable/c/8922c7940bae9ce4b1736dddb6362370793835c2
- https://git.kernel.org/stable/c/8f90405a4a6f1f1880dc07996b47bf57c712bd8a
- https://git.kernel.org/stable/c/91047a4396a8b1857a6f712a90cf33ec0012b189
- https://git.kernel.org/stable/c/b66774b48dd98f07254951f74ea6f513efe7ff8b
- https://git.kernel.org/stable/c/d3b739db5dc6f688a60d56da872fabaf65246032
JSON original (NVD)
Mostrar
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{
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref\n\nl2cap_chan_timeout() runs asynchronously and accesses chan->conn. If\nthe connection is torn down while the timer is running or pending,\nchan->conn can be freed, leading to a use-after-free when the timer\nworker attempts to lock conn->lock:\n\n| BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n| BUG: KASAN: slab-use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n| BUG: KASAN: slab-use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n| BUG: KASAN: slab-use-after-free in mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n| Write of size 8 at addr ffff8881298d9550 by task kworker/2:1/83\n|\n| CPU: 2 UID: 0 PID: 83 Comm: kworker/2:1 Not tainted 7.1.0-rc6-next-20260601-dirty #6 PREEMPT(full)\n| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014\n| Workqueue: events l2cap_chan_timeout\n| Call Trace:\n| <TASK>\n| instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n| atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n| __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n| mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n| l2cap_chan_timeout+0x5d/0x1b0 net/bluetooth/l2cap_core.c:422\n| process_one_work kernel/workqueue.c:3326 [inline]\n| process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n| worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n| kthread+0x346/0x430 kernel/kthread.c:436\n| ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n| ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n| </TASK>\n|\n| Allocated by task 320:\n| l2cap_conn_add+0xa7/0x820 net/bluetooth/l2cap_core.c:7075\n| l2cap_connect_cfm+0xdb/0xd70 net/bluetooth/l2cap_core.c:7452\n| hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]\n| hci_remote_features_evt+0x52f/0x9f0 net/bluetooth/hci_event.c:3760\n| hci_event_func net/bluetooth/hci_event.c:7796 [inline]\n| hci_event_packet+0x561/0xa70 net/bluetooth/hci_event.c:7847\n| hci_rx_work+0x370/0x890 net/bluetooth/hci_core.c:4040\n| process_one_work kernel/workqueue.c:3326 [inline]\n| process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n| worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n| kthread+0x346/0x430 kernel/kthread.c:436\n| ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n| ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|\n| Freed by task 322:\n| hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline]\n| hci_conn_hash_flush+0x101/0x1f0 net/bluetooth/hci_conn.c:2736\n| hci_dev_close_sync+0x889/0xde0 net/bluetooth/hci_sync.c:5405\n| hci_dev_do_close net/bluetooth/hci_core.c:502 [inline]\n| hci_unregister_dev+0x1f7/0x370 net/bluetooth/hci_core.c:2679\n| vhci_release+0x12a/0x180 drivers/bluetooth/hci_vhci.c:690\n| __fput+0x369/0x890 fs/file_table.c:510\n| task_work_run+0x160/0x1d0 kernel/task_work.c:233\n| get_signal+0xf5b/0x1120 kernel/signal.c:2810\n| arch_do_signal_or_restart+0x4d/0x600 arch/x86/kernel/signal.c:337\n| __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]\n| exit_to_user_mode_loop+0x85/0x510 kernel/entry/common.c:98\n| do_syscall_64+0x263/0x3d0 arch/x86/entry/syscall_64.c:100\n| entry_SYSCALL_64_after_hwframe+0x77/0x7f\n|\n| The buggy address belongs to the object at ffff8881298d9400\n| which belongs to the cache kmalloc-512 of size 512\n| The buggy address is located 336 bytes inside of\n| freed 512-byte region [ffff8881298d9400, ffff8881298d9600)\n\nFix it by having chan->conn hold a reference to l2cap_conn (via\nl2cap_conn_get) when the channel is added to the connection, and\nreleasing it in the channel destructor. This ensures the l2cap_conn\nremains alive as long as the channel exists.\n\nA new FLAG_DEL channel flag is introduced to indicate that the ch\n---truncated---"
}
],
"lastModified": "2026-09-03T18:22:07.563",
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