CVE-2026-72335 Bluetooth: MGMT: Fix adv monitor add failure cleanup
A use-after-free vulnerability in the Linux kernel Bluetooth subsystem allows attackers to cause a denial of service or potentially execute code via crafted management commands.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72335?
CVE-2026-72335 is a high-severity use after free vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: MGMT: Fix adv monitor add failure cleanup
hci_add_adv_monitor() publishes a new adv_monitor in hdev->adv_monitors_idr before the powered MSFT setup step. The MSFT offload add path can then fail either locally before the controller add command completes, or in the MSFT add callback. In the current queued management add flow, hci_cmd_sync_work() still invokes mgmt_add_adv_patterns_monitor_complete() with the original pending command after msft_add_monitor_pattern() returns.
The buggy scenario involves two paths, with each column showing the order within that path:
MSFT add handling MGMT completion 1. insert monitor and handle 1. receive sync error 2. send MSFT add command 2. call add-monitor completion 3. callback sees bad response 3. load cmd->user_data 4. callback frees monitor 4. read monitor->handle
Local MSFT setup failures have the other half of the same ownership bug: they return an error after the IDR insertion, but no later code removes the failed monitor from the IDR.
Keep ownership with the pending management command until its completion. For normal management adds, the MSFT add callback now records successful controller state and returns errors to its caller. The management completion frees the monitor on non-success after copying the response handle, while resume/reregister callback-error cleanup remains in the MSFT callback. The success path keeps the existing bookkeeping.
Validation reproduced this kernel report: BUG: KASAN: slab-use-after-free in mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth]
Call Trace: <TASK> dump_stack_lvl+0x66/0xa0 print_report+0xce/0x5f0 ? mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth] ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x19f/0x330 ? mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth] kasan_report+0xe0/0x110 ? mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth] mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth] ? srso_alias_return_thunk+0x5/0xfbef5 ? 0xffffffffc00d00da ? __pfx_mgmt_add_adv_patterns_monitor_complete+0x10/0x10 [bluetooth] ? __pfx_mgmt_add_adv_patterns_monitor_complete+0x10/0x10 [bluetooth] ? hci_cmd_sync_work+0x1ab/0x210 [bluetooth] hci_cmd_sync_work+0x1c0/0x210 [bluetooth] ? __pfx_mgmt_add_adv_patterns_monitor_complete+0x10/0x10 [bluetooth] process_one_work+0x4fd/0xbc0 ? __pfx_process_one_work+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? __list_add_valid_or_report+0x37/0xf0 ? __pfx_hci_cmd_sync_work+0x10/0x10 [bluetooth] ? srso_alias_return_thunk+0x5/0xfbef5 worker_thread+0x2d8/0x570 ? __pfx_worker_thread+0x10/0x10 kthread+0x1ad/0x1f0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x3c9/0x540 ? __pfx_ret_from_fork+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __switch_to+0x2e9/0x730 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK>
Allocated by task 471 on cpu 3 at 285.205389s: kasan_save_stack+0x33/0x60 kasan_save_track+0x17/0x60 __kasan_kmalloc+0xaa/0xb0 add_adv_patterns_monitor_rssi+0xd5/0x230 [bluetooth] hci_sock_sendmsg+0x96b/0xf80 [bluetooth] __sys_sendto+0x2bc/0x2d0 __x64_sys_sendto+0x76/0x90 do_syscall_64+0x115/0x6a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 454 on cpu 2 at 285.217112s: kasan_save_stack+0x33/0x60 kasan_save_track+0x17/0x60 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x313/0x590 msft_add_monitor_sync+0x54a/0x570 [bluetooth] hci_add_adv_monitor+0x133/0x180 [bluetooth] hci_cmd_sync_work+0x187/0x210 [bluetooth] process_one_work+0x4fd/0xbc0 worker_thread+0x2d8/0x570 kthread+0x1ad/0x1f0 ret_from_fork+0x3c9/0x540 ret_from_fork_asm+0x1a/0x30
Which versions are affected by CVE-2026-72335?
How do I fix CVE-2026-72335?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-72335 being exploited?
There is no known exploitation of CVE-2026-72335 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72335, DEBIAN-CVE-2026-72335, GHSA-3hg2-6vgw-gv3f, UBUNTU-CVE-2026-72335.