{"id":"CVE-2026-64434","summary":"Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref","details":"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-\u003econn. If\nthe connection is torn down while the timer is running or pending,\nchan-\u003econn can be freed, leading to a use-after-free when the timer\nworker attempts to lock conn-\u003elock:\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|  \u003cTASK\u003e\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|  \u003c/TASK\u003e\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-\u003econn 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---","modified":"2026-11-13T04:06:31.294808114Z","published":"2026-07-25T08:51:09.066Z","related":["SUSE-SU-2026:23477-1","SUSE-SU-2026:23481-1","SUSE-SU-2026:23528-1","SUSE-SU-2026:23529-1","SUSE-SU-2026:23881-1","SUSE-SU-2026:23887-1","SUSE-SU-2026:23897-1","SUSE-SU-2026:23902-1","SUSE-SU-2026:24550-1","SUSE-SU-2026:24619-1","SUSE-SU-2026:24643-1","SUSE-SU-2026:24648-1","SUSE-SU-2026:24651-1","SUSE-SU-2026:24662-1","SUSE-SU-2026:4120-1","SUSE-SU-2026:4254-1","SUSE-SU-2026:5091-1","openSUSE-SU-2026:11476-1","openSUSE-SU-2026:21910-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64434.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0b0e2bf39cf99e458d991b9df253727e036a7d7d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/50c38d9f42a529691e4e67ea9cedf4f0bfc8d277"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8922c7940bae9ce4b1736dddb6362370793835c2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8f90405a4a6f1f1880dc07996b47bf57c712bd8a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/91047a4396a8b1857a6f712a90cf33ec0012b189"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b66774b48dd98f07254951f74ea6f513efe7ff8b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d3b739db5dc6f688a60d56da872fabaf65246032"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64434.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64434"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3634cbdc2eb414b69ffa752ddbe5e0458518e321"},{"fixed":"8f90405a4a6f1f1880dc07996b47bf57c712bd8a"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e1c100e2d61bd8c718b7d91fe3e050780a9bf72d"},{"fixed":"32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9"},{"fixed":"8922c7940bae9ce4b1736dddb6362370793835c2"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"89dec92041717b027216e110599e4f6d6c921b79"},{"fixed":"91047a4396a8b1857a6f712a90cf33ec0012b189"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"50dfec218808b148ab4247b1858031b7a32015c5"},{"fixed":"0b0e2bf39cf99e458d991b9df253727e036a7d7d"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"859d3ace791ed878ae9ba5522c7844d960da8f88"},{"fixed":"d3b739db5dc6f688a60d56da872fabaf65246032"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8c8e620467a7b51562dbcefbd1f09f288d7d710d"},{"fixed":"50c38d9f42a529691e4e67ea9cedf4f0bfc8d277"},{"fixed":"b66774b48dd98f07254951f74ea6f513efe7ff8b"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7555fd885a0603f50e49a655850a1f2bd8a25398"}]}],"versions":["v5.10.264","v5.10.263","v5.10.262","v5.10.261","v5.10.260","v5.10.259","v5.15.215","v5.15.214","v5.15.213","v5.15.212","v5.15.211","v5.15.210","v6.1.182","v6.1.181","v6.1.180","v6.1.179","v6.1.178","v6.1.177","v6.1.176","v6.6.144","v6.6.143","v6.12.96","v6.12.95","v6.12.94","v6.12.93","v6.18.38","v6.18.37","v6.18.36","v6.18.35","v7.0.14","v7.0.13","v7.0.12"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64434.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.10.259"},{"fixed":"5.10.265"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.15.210"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.1.176"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.6.143"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.12.93"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.18.35"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"7.0.12"},{"fixed":"7.1"}]},{"type":"ECOSYSTEM","events":[{"introduced":"7.1.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64434.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}