{"id":"CVE-2026-64434","title":"Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref","summary":"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…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 3634cbdc2eb414b69ffa752ddbe5e0458518e321 < 8f90405a4a6f1f1880dc07996b47bf57c712bd8a","Linux >= e1c100e2d61bd8c718b7d91fe3e050780a9bf72d < 32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b","Linux >= deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9 < 8922c7940bae9ce4b1736dddb6362370793835c2","Linux >= 89dec92041717b027216e110599e4f6d6c921b79 < 91047a4396a8b1857a6f712a90cf33ec0012b189","Linux >= 50dfec218808b148ab4247b1858031b7a32015c5 < 0b0e2bf39cf99e458d991b9df253727e036a7d7d","Linux >= 859d3ace791ed878ae9ba5522c7844d960da8f88 < d3b739db5dc6f688a60d56da872fabaf65246032","Linux >= 8c8e620467a7b51562dbcefbd1f09f288d7d710d < 50c38d9f42a529691e4e67ea9cedf4f0bfc8d277","Linux >= 8c8e620467a7b51562dbcefbd1f09f288d7d710d < b66774b48dd98f07254951f74ea6f513efe7ff8b","Linux 7555fd885a0603f50e49a655850a1f2bd8a25398","Linux >= 5.10.259 < 5.10.265","Linux >= 5.15.210 < 5.15.216","Linux >= 6.1.176 < 6.1.183","Linux >= 6.6.143 < 6.6.145","Linux >= 6.12.93 < 6.12.97","Linux >= 6.18.35 < 6.18.39","Linux >= 7.0.12 < 7.1","Linux 7.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:40:36.220743Z"},"published":"2026-07-25","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:42:35.391Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64434","references":[{"url":"https://git.kernel.org/stable/c/8f90405a4a6f1f1880dc07996b47bf57c712bd8a"},{"url":"https://git.kernel.org/stable/c/32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b"},{"url":"https://git.kernel.org/stable/c/8922c7940bae9ce4b1736dddb6362370793835c2"},{"url":"https://git.kernel.org/stable/c/91047a4396a8b1857a6f712a90cf33ec0012b189"},{"url":"https://git.kernel.org/stable/c/0b0e2bf39cf99e458d991b9df253727e036a7d7d"},{"url":"https://git.kernel.org/stable/c/d3b739db5dc6f688a60d56da872fabaf65246032"},{"url":"https://git.kernel.org/stable/c/50c38d9f42a529691e4e67ea9cedf4f0bfc8d277"},{"url":"https://git.kernel.org/stable/c/b66774b48dd98f07254951f74ea6f513efe7ff8b"}],"tags":["cve.org"],"epss":0.00255,"epssPercentile":0.15954,"ingestedAt":"2026-10-16T17:24:46.819Z","slug":"CVE-2026-64434","body":"## Overview\n\nIn 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---\n\n## Affected\n\n- `Linux >= 3634cbdc2eb414b69ffa752ddbe5e0458518e321 < 8f90405a4a6f1f1880dc07996b47bf57c712bd8a`\n- `Linux >= e1c100e2d61bd8c718b7d91fe3e050780a9bf72d < 32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b`\n- `Linux >= deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9 < 8922c7940bae9ce4b1736dddb6362370793835c2`\n- `Linux >= 89dec92041717b027216e110599e4f6d6c921b79 < 91047a4396a8b1857a6f712a90cf33ec0012b189`\n- `Linux >= 50dfec218808b148ab4247b1858031b7a32015c5 < 0b0e2bf39cf99e458d991b9df253727e036a7d7d`\n- `Linux >= 859d3ace791ed878ae9ba5522c7844d960da8f88 < d3b739db5dc6f688a60d56da872fabaf65246032`\n- `Linux >= 8c8e620467a7b51562dbcefbd1f09f288d7d710d < 50c38d9f42a529691e4e67ea9cedf4f0bfc8d277`\n- `Linux >= 8c8e620467a7b51562dbcefbd1f09f288d7d710d < b66774b48dd98f07254951f74ea6f513efe7ff8b`\n- `Linux 7555fd885a0603f50e49a655850a1f2bd8a25398`\n- `Linux >= 5.10.259 < 5.10.265`\n- `Linux >= 5.15.210 < 5.15.216`\n- `Linux >= 6.1.176 < 6.1.183`\n- `Linux >= 6.6.143 < 6.6.145`\n- `Linux >= 6.12.93 < 6.12.97`\n- `Linux >= 6.18.35 < 6.18.39`\n- `Linux >= 7.0.12 < 7.1`\n- `Linux 7.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}