--- id: CVE-2025-39860 title: 'Bluetooth: Fix use-after-free in l2cap_sock_cleanup_listen()' summary: |- In the Linux kernel, the following vulnerability has been resolved: Bluetooth: Fix use-after-free in l2cap_sock_cleanup_listen() syzbot reported the splat below without a repro. In the splat, a single thread calling bt_accept_dequeue(… severity: high cvss: 8 cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H' cvssSource: cna vendor: Linux product: Linux affected: - >- Linux >= a2da00d1ea1abfb04f846638e210b5b5166e3c9c < 964cbb198f9c46c2b2358cd1faffc04c1e8248cf - >- Linux >= 06f87c96216bc5cd1094c23492274f77f1d5dd3b < 83e1d9892ef51785cf0760b7681436760dda435a - >- Linux >= fbe5a2fed8156cc19eb3b956602b0a1dd46a302d < 47f6090bcf75c369695d21c3f179db8a56bbbd49 - >- Linux >= 29fac18499332211b2615ade356e2bd8b3269f98 < 2ca99fc3512a8074de20ee52a87b492dfcc41a4d - >- Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 6077d16b5c0f65d571eee709de2f0541fb5ef0ca - >- Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 306b0991413b482dbf5585b423022123bb505966 - >- Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 3dff390f55ccd9ce12e91233849769b5312180c2 - >- Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 862c628108562d8c7a516a900034823b381d3cba - Linux 51822644a047eac2310fab0799b64e3430b5a111 - Linux 82cdb2ccbe43337798393369f0ceb98699fe6037 - Linux 10426afe65c8bf7b24dd0c7be4dcc65f86fc99f9 - Linux >= 5.4.253 < 5.4.299 - Linux >= 5.10.190 < 5.10.243 - Linux >= 5.15.126 < 5.15.192 - Linux >= 6.1.45 < 6.1.151 - Linux >= 4.14.322 < 4.15 - Linux >= 4.19.291 < 4.20 - Linux >= 6.4.10 < 6.5 - Linux 6.5 ssvc: exploitation: none automatable: 'no' technicalImpact: total timestamp: '2026-10-15T21:54:24.494411Z' published: '2025-09-19' updated: '2026-10-15' sourceUpdated: '2026-10-15T22:02:32.480Z' source: CVEORG sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-39860' references: - url: 'https://git.kernel.org/stable/c/964cbb198f9c46c2b2358cd1faffc04c1e8248cf' - url: 'https://git.kernel.org/stable/c/83e1d9892ef51785cf0760b7681436760dda435a' - url: 'https://git.kernel.org/stable/c/47f6090bcf75c369695d21c3f179db8a56bbbd49' - url: 'https://git.kernel.org/stable/c/2ca99fc3512a8074de20ee52a87b492dfcc41a4d' - url: 'https://git.kernel.org/stable/c/6077d16b5c0f65d571eee709de2f0541fb5ef0ca' - url: 'https://git.kernel.org/stable/c/306b0991413b482dbf5585b423022123bb505966' - url: 'https://git.kernel.org/stable/c/3dff390f55ccd9ce12e91233849769b5312180c2' - url: 'https://git.kernel.org/stable/c/862c628108562d8c7a516a900034823b381d3cba' tags: - cve.org epss: 0.00231 epssPercentile: 0.14075 ingestedAt: '2026-10-15T22:48:25.528Z' --- ## Overview In the Linux kernel, the following vulnerability has been resolved: Bluetooth: Fix use-after-free in l2cap_sock_cleanup_listen() syzbot reported the splat below without a repro. In the splat, a single thread calling bt_accept_dequeue() freed sk and touched it after that. The root cause would be the racy l2cap_sock_cleanup_listen() call added by the cited commit. bt_accept_dequeue() is called under lock_sock() except for l2cap_sock_release(). Two threads could see the same socket during the list iteration in bt_accept_dequeue(): CPU1 CPU2 (close()) ---- ---- sock_hold(sk) sock_hold(sk); lock_sock(sk) <-- block close() sock_put(sk) bt_accept_unlink(sk) sock_put(sk) <-- refcnt by bt_accept_enqueue() release_sock(sk) lock_sock(sk) sock_put(sk) bt_accept_unlink(sk) sock_put(sk) <-- last refcnt bt_accept_unlink(sk) <-- UAF Depending on the timing, the other thread could show up in the "Freed by task" part. Let's call l2cap_sock_cleanup_listen() under lock_sock() in l2cap_sock_release(). [0]: BUG: KASAN: slab-use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline] BUG: KASAN: slab-use-after-free in do_raw_spin_lock+0x26f/0x2b0 kernel/locking/spinlock_debug.c:115 Read of size 4 at addr ffff88803b7eb1c4 by task syz.5.3276/16995 CPU: 3 UID: 0 PID: 16995 Comm: syz.5.3276 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xcd/0x630 mm/kasan/report.c:482 kasan_report+0xe0/0x110 mm/kasan/report.c:595 debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline] do_raw_spin_lock+0x26f/0x2b0 kernel/locking/spinlock_debug.c:115 spin_lock_bh include/linux/spinlock.h:356 [inline] release_sock+0x21/0x220 net/core/sock.c:3746 bt_accept_dequeue+0x505/0x600 net/bluetooth/af_bluetooth.c:312 l2cap_sock_cleanup_listen+0x5c/0x2a0 net/bluetooth/l2cap_sock.c:1451 l2cap_sock_release+0x5c/0x210 net/bluetooth/l2cap_sock.c:1425 __sock_release+0xb3/0x270 net/socket.c:649 sock_close+0x1c/0x30 net/socket.c:1439 __fput+0x3ff/0xb70 fs/file_table.c:468 task_work_run+0x14d/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2accf8ebe9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffdb6cb1378 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00000000000426fb RCX: 00007f2accf8ebe9 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f2acd1b7da0 R08: 0000000000000001 R09: 00000012b6cb166f R10: 0000001b30e20000 R11: 0000000000000246 R12: 00007f2acd1b609c R13: 00007f2acd1b6090 R14: ffffffffffffffff R15: 00007ffdb6cb1490 Allocated by task 5326: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4365 [inline] __kmalloc_nopro ---truncated--- ## Affected - `Linux >= a2da00d1ea1abfb04f846638e210b5b5166e3c9c < 964cbb198f9c46c2b2358cd1faffc04c1e8248cf` - `Linux >= 06f87c96216bc5cd1094c23492274f77f1d5dd3b < 83e1d9892ef51785cf0760b7681436760dda435a` - `Linux >= fbe5a2fed8156cc19eb3b956602b0a1dd46a302d < 47f6090bcf75c369695d21c3f179db8a56bbbd49` - `Linux >= 29fac18499332211b2615ade356e2bd8b3269f98 < 2ca99fc3512a8074de20ee52a87b492dfcc41a4d` - `Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 6077d16b5c0f65d571eee709de2f0541fb5ef0ca` - `Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 306b0991413b482dbf5585b423022123bb505966` - `Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 3dff390f55ccd9ce12e91233849769b5312180c2` - `Linux >= 1728137b33c00d5a2b5110ed7aafb42e7c32e4a1 < 862c628108562d8c7a516a900034823b381d3cba` - `Linux 51822644a047eac2310fab0799b64e3430b5a111` - `Linux 82cdb2ccbe43337798393369f0ceb98699fe6037` - `Linux 10426afe65c8bf7b24dd0c7be4dcc65f86fc99f9` - `Linux >= 5.4.253 < 5.4.299` - `Linux >= 5.10.190 < 5.10.243` - `Linux >= 5.15.126 < 5.15.192` - `Linux >= 6.1.45 < 6.1.151` - `Linux >= 4.14.322 < 4.15` - `Linux >= 4.19.291 < 4.20` - `Linux >= 6.4.10 < 6.5` - `Linux 6.5` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges.