CVE-2025-40309
NoneCVSS
—
EPSS
0.2%
Published
Dec 8, 2025
CISA due date
—
Cloudanix analysis
A flaw in how the Linux kernel cleans up Bluetooth audio connections can let attackers crash the computer or potentially take control.
- Exploitation
- Local Privilege
- Attacker needs
- Local User
- Complexity
- Moderate
- Impact
- Full Compromise
- Component
- OS kernel
- Class
- Use After Free
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Use-after-free in Linux kernel Bluetooth SCO connection handling where sco_conn_put decrements a kref leading to sco_conn_free on already-freed socket memory during HCI connection failure paths in workqueues.
Why it matters to the business
Linux systems using Bluetooth SCO audio profiles face risk of kernel crashes or potential local privilege escalation, disrupting wireless audio and requiring urgent kernel updates across fleets.
How an attack unfolds
An attacker initiates or interferes with SCO Bluetooth connections to trigger connection failures; this schedules hci_cmd_sync_work that calls hci_conn_del and sco_connect_cfm, reaching the UAF in sco_conn_put on a freed sk_buff structure.
How to fix it
Upgrade the Linux kernel to a version containing commit 391f83547b7b2c63e4b572ab838e10a06cfa4425 in net/bluetooth/sco.c; rebuild and reboot all affected hosts.
How to confirm the fix worked
Confirm the commit is present in the kernel tree, run Bluetooth SCO connection and failure test cases, and verify absence of KASAN reports for sco_conn_free.
Typical attack path
- Create or accept SCO socket via bt_sock_create
- Trigger HCI connection attempt that later fails
- Invoke hci_abort_conn_sync and hci_conn_unlink
- Reach sco_conn_put during kref_put on freed object
- Perform write or dereference on the use-after-free memory
How to detect it
Search kernel logs and dmesg for KASAN slab-use-after-free reports mentioning sco_conn_free, sco_conn_put, or net/bluetooth/sco.c during hci_conn_failed or workqueue activity.
What your security team should do
- Prioritize kernel update on all systems exposing Bluetooth
- Temporarily disable SCO or Bluetooth profiles where feasible
- Monitor kernel logs for KASAN or slab-use-after-free entries referencing sco.c
- Review downstream dependent packages for rebuilt kernels
The record
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SCO: Fix UAF on sco_conn_free BUG: KASAN: slab-use-after-free in sco_conn_free net/bluetooth/sco.c:87 [inline] BUG: KASAN: slab-use-after-free in kref_put include/linux/kref.h:65 [inline] BUG: KASAN: slab-use-after-free in sco_conn_put+0xdd/0x410 net/bluetooth/sco.c:107 Write of size 8 at addr ffff88811cb96b50 by task kworker/u17:4/352 CPU: 1 UID: 0 PID: 352 Comm: kworker/u17:4 Not tainted 6.17.0-rc5-g717368f83676 #4 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Workqueue: hci13 hci_cmd_sync_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x10b/0x170 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x191/0x550 mm/kasan/report.c:482 kasan_report+0xc4/0x100 mm/kasan/report.c:595 sco_conn_free net/bluetooth/sco.c:87 [inline] kref_put include/linux/kref.h:65 [inline] sco_conn_put+0xdd/0x410 net/bluetooth/sco.c:107 sco_connect_cfm+0xb4/0xae0 net/bluetooth/sco.c:1441 hci_connect_cfm include/net/bluetooth/hci_core.h:2082 [inline] hci_conn_failed+0x20a/0x2e0 net/bluetooth/hci_conn.c:1313 hci_conn_unlink+0x55f/0x810 net/bluetooth/hci_conn.c:1121 hci_conn_del+0xb6/0x1110 net/bluetooth/hci_conn.c:1147 hci_abort_conn_sync+0x8c5/0xbb0 net/bluetooth/hci_sync.c:5689 hci_cmd_sync_work+0x281/0x380 net/bluetooth/hci_sync.c:332 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0x77e/0x1040 kernel/workqueue.c:3319 worker_thread+0xbee/0x1200 kernel/workqueue.c:3400 kthread+0x3c7/0x870 kernel/kthread.c:463 ret_from_fork+0x13a/0x1e0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> Allocated by task 31370: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x30/0x70 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0x82/0x90 mm/kasan/common.c:405 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4382 [inline] __kmalloc_noprof+0x22f/0x390 mm/slub.c:4394 kmalloc_noprof include/linux/slab.h:909 [inline] sk_prot_alloc+0xae/0x220 net/core/sock.c:2239 sk_alloc+0x34/0x5a0 net/core/sock.c:2295 bt_sock_alloc+0x3c/0x330 net/bluetooth/af_bluetooth.c:151 sco_sock_alloc net/bluetooth/sco.c:562 [inline] sco_sock_create+0xc0/0x350 net/bluetooth/sco.c:593 bt_sock_create+0x161/0x3b0 net/bluetooth/af_bluetooth.c:135 __sock_create+0x3ad/0x780 net/socket.c:1589 sock_create net/socket.c:1647 [inline] __sys_socket_create net/socket.c:1684 [inline] __sys_socket+0xd5/0x330 net/socket.c:1731 __do_sys_socket net/socket.c:1745 [inline] __se_sys_socket net/socket.c:1743 [inline] __x64_sys_socket+0x7a/0x90 net/socket.c:1743 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc7/0x240 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 31374: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x30/0x70 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x3d/0x50 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2428 [inline] slab_free mm/slub.c:4701 [inline] kfree+0x199/0x3b0 mm/slub.c:4900 sk_prot_free net/core/sock.c:2278 [inline] __sk_destruct+0x4aa/0x630 net/core/sock.c:2373 sco_sock_release+0x2ad/0x300 net/bluetooth/sco.c:1333 __sock_release net/socket.c:649 [inline] sock_close+0xb8/0x230 net/socket.c:1439 __fput+0x3d1/0x9e0 fs/file_table.c:468 task_work_run+0x206/0x2a0 kernel/task_work.c:227 get_signal+0x1201/0x1410 kernel/signal.c:2807 arch_do_signal_or_restart+0x34/0x740 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x68/0xc0 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] s ---truncated---
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 0 | 5.4.302 |
| Linux | Kernel | 6.13.0 | 6.17.8 |
| Mageia:9 | kernel | 0 | 6.6.120-1.mga9 |
| Mageia:9 | kernel-linus | 0 | 6.6.120-1.mga9 |
| Mageia:9 | kmod-virtualbox | 0 | 7.1.14-14.mga9 |
| Mageia:9 | kmod-xtables-addons | 0 | 3.24-88.mga9 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_19 | 0 | 1-150600.13.3.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 16.0 | dtb-aarch64 | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-64kb | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-azure | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-default | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-default-base | 0 | 6.12.0-160000.9.1.160000.2.6 |
| openSUSE:Leap 16.0 | kernel-docs | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-kvmsmall | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-obs-build | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-obs-qa | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-rt | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-source | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-syms | 0 | 6.12.0-160000.9.1 |
| openSUSE:Leap 16.0 | kernel-zfcpdump | 0 | 6.12.0-160000.9.1 |
Related vulnerabilities
- CVE-2026-23226 In the Linux kernel, the following vulnerability has been resolved: ksmbd: add chann_lock… Also affects Kernel
- CVE-2026-23225 In the Linux kernel, the following vulnerability has been resolved: sched/mmcid: Don't… Also affects Kernel
- CVE-2026-23230 In the Linux kernel, the following vulnerability has been resolved: smb: client: split… Also affects Kernel
- CVE-2026-23224 In the Linux kernel, the following vulnerability has been resolved: erofs: fix UAF issue… Also affects Kernel
- CVE-2026-23227 In the Linux kernel, the following vulnerability has been resolved: drm/exynos: vidi: use… Also affects Kernel
- CVE-2026-23223 In the Linux kernel, the following vulnerability has been resolved: xfs: fix UAF in… Also affects Kernel
- CVE-2026-23228 In the Linux kernel, the following vulnerability has been resolved: smb: server: fix leak… Also affects Kernel
- CVE-2026-23229 In the Linux kernel, the following vulnerability has been resolved: crypto: virtio - Add… Also affects Kernel