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Linux Kernel CVE-2025-40309

| EUVDEUVD-2025-201636 HIGH
2025-12-08 416baaa9-dc9f-4396-8d5f-8c081fb06d67
8.0
CVSS 3.1 · Vendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
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Severity by source

Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67) PRIMARY
8.0 HIGH
AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
7.0 HIGH

Local SCO socket access needed (AV:L/PR:L), and it is a timing-dependent teardown race (AC:H); UAF write can yield DoS and potential LPE (C/I/A:H).

3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
7.0 HIGH
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Red Hat
6.4 MEDIUM
qualitative

Primary rating from Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67).

CVSS VectorVendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

6
CVSS changed
Jul 30, 2026 - 06:37 NVD
8.0 (HIGH)
Patch released
Mar 16, 2026 - 15:00 nvd
Patch available
EUVD ID Assigned
Mar 15, 2026 - 17:54 euvd
EUVD-2025-201636
Analysis Generated
Mar 15, 2026 - 17:54 vuln.today
CVE Published
Dec 08, 2025 - 01:16 cve.org
HIGH 8.0
CVE Published
Dec 08, 2025 - 01:16 nvd
N/A

DescriptionCVE.org

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---

AnalysisAI

Memory corruption (use-after-free) in the Linux kernel's Bluetooth SCO (Synchronous Connection-Oriented) socket subsystem allows a local attacker with Bluetooth socket access to trigger a slab use-after-free during connection teardown. The flaw affects net/bluetooth/sco.c, where sco_conn_free/sco_conn_put in the HCI command-sync workqueue can operate on a sco_conn object whose backing socket was already freed by a concurrent sco_sock_release, leading to a kernel write to freed memory. Rated CVSS 8.0 with a fix already merged upstream and shipped in stable kernels; no public exploit is identified and EPSS is very low (0.03%).

Technical ContextAI

The vulnerable component is the Bluetooth SCO protocol handler in the Linux kernel networking stack (net/bluetooth/sco.c), which manages synchronous voice/audio links over HCI. sco_conn objects are reference-counted via kref; a socket is allocated through sco_sock_create → bt_sock_alloc → sk_alloc and later torn down via sco_sock_release → __sk_destruct → sk_prot_free (kfree). The KASAN trace shows a race: task A frees the sk via sco_sock_release while the hci_cmd_sync_work kworker independently reaches sco_connect_cfm → hci_conn_failed → sco_conn_put, dereferencing/writing (kref_put, 8-byte write) the freed connection structure. This is a classic concurrency-driven use-after-free (CWE-416 class, though CWE is listed N/A in the input), rooted in insufficient lifetime synchronization between the socket-release path and the asynchronous connection-confirmation callback path.

RemediationAI

Vendor-released patch: update to a fixed stable kernel - 5.4.302, 5.10.247, 5.15.197, 6.1.159, 6.6.117, 6.12.58, or 6.17.8 (or later within each series), matching whichever branch your system tracks. Distro users should apply the packaged updates referenced in Ubuntu USN-8095-1 (https://ubuntu.com/security/notices/USN-8095-1) and USN-8096-1 (https://ubuntu.com/security/notices/USN-8096-1) and reboot into the new kernel. If immediate patching is not possible, reduce exposure by disabling the Bluetooth stack where it is not needed (unload the bluetooth/bnep/sco modules or blacklist them via modprobe), which prevents SCO socket creation entirely at the cost of losing all Bluetooth functionality; on servers this is usually acceptable. Where Bluetooth is required, restrict local account access and avoid exposing the host to untrusted Bluetooth peers, understanding this only narrows, not eliminates, the race window. Fix commits are at git.kernel.org/stable/c/391f83547b7b2c63e4b572ab838e10a06cfa4425 and related hashes listed in the references.

Vendor StatusVendor

SUSE

Severity: Important
Product Status
Container suse/sl-micro/6.0/baremetal-os-container:latest Affected
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.95 Affected
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.115 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.146 Affected
Container suse/sl-micro/6.0/toolbox:latest Affected

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CVE-2025-40309 vulnerability details – vuln.today

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