CVE-2026-72336
Bluetooth: 6lowpan: hold L2CAP conn across debugfs control
Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: 6lowpan: hold L2CAP conn across debugfs control get_l2cap_conn() looks up an LE hci_conn under hdev protection, but then drops that protection before reading hcon->l2cap_data and before lowpan_control_write() later dereferences conn->hcon. A disconnect or device close can tear down the same L2CAP connection in that window. The buggy scenario involves two paths, with each column showing the order within that path: 6LoWPAN control write: HCI disconnect/device close: 1. get_l2cap_conn() finds hcon 1. hci_disconn_cfm() dispatches and hcon->l2cap_data. the L2CAP disconnect callback. 2. get_l2cap_conn() drops hdev 2. l2cap_conn_del() clears protection and returns conn. hcon->l2cap_data and drops the L2CAP connection reference. 3. lowpan_control_write() reads 3. hci_conn_del() removes and drops conn->hcon. the HCI connection. Take a reference to the L2CAP connection with l2cap_conn_hold_unless_zero() while hdev is still locked, and drop that reference after the debugfs command's last use of conn. This mirrors the existing L2CAP ACL receive-side handoff and keeps the connection dereferenceable after leaving hdev protection. Export the existing helper so the bluetooth_6lowpan module can use the same lifetime primitive. Validation reproduced this kernel report: BUG: KASAN: slab-use-after-free in lowpan_control_write+0x374/0x520 The buggy address belongs to the object at ffff888111b9d000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 0 bytes inside of freed 1024-byte region [ffff888111b9d000, ffff888111b9d400) Read of size 8 Call trace: dump_stack_lvl+0x66/0xa0 print_report+0xce/0x5f0 lowpan_control_write+0x374/0x520 (net/bluetooth/6lowpan.c:1131) srso_alias_return_thunk+0x5/0xfbef5 __virt_addr_valid+0x19f/0x330 kasan_report+0xe0/0x110 __debugfs_file_get+0xf7/0x400 full_proxy_write+0x9e/0xd0 vfs_write+0x1b0/0x810 ksys_write+0xd2/0x170 dnotify_flush+0x32/0x220 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x17/0x60 __kasan_kmalloc+0xaa/0xb0 l2cap_conn_add+0x45/0x520 l2cap_chan_connect+0xac6/0xd90 l2cap_sock_connect+0x216/0x350 __sys_connect+0x101/0x130 __x64_sys_connect+0x40/0x50 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x17/0x60 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x313/0x590 hci_conn_hash_flush+0xc0/0x140 hci_dev_close_sync+0x41a/0xb00 hci_dev_close+0x12f/0x160 hci_sock_ioctl+0x157/0x570 sock_do_ioctl+0xf7/0x210 sock_ioctl+0x32f/0x490 __x64_sys_ioctl+0xc7/0x110 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f kasan_record_aux_stack+0xa7/0xc0 insert_work+0x32/0x100 __queue_work+0x262/0xa60 queue_work_on+0xad/0xb0 l2cap_connect_cfm+0x4ef/0x670 hci_le_remote_feat_complete_evt+0x247/0x430 hci_event_packet+0x360/0x6f0 hci_rx_work+0x2ae/0x7a0 process_one_work+0x4fd/0xbc0 worker_thread+0x2d8/0x570 kthread+0x1ad/0x1f0 ret_from_fork+0x3c9/0x540 ret_from_fork_asm+0x1a/0x30
INFO
Published Date :
Aug. 15, 2026, 6:22 a.m.
Last Modified :
Aug. 17, 2026, 6:18 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Take L2CAP connection reference with l2cap_conn_hold_unless_zero.
- Drop reference after last use of connection.
- Export helper for bluetooth_6lowpan module.
- Apply relevant kernel patches.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-72336.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-72336 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-72336
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-72336 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-72336 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2026
Action Type Old Value New Value Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': 'ba1f1ef6522e63aa5dd29805b4390ea2ccadf05e', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': 'd2a8dc1f619c9e0e4126bee795c39ebddd2ec8ff', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '23a83bac3356e7b211bcdcf581a31f7b536a2c24', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '32c48c7f6cc8c7888e46a8c81622154ccafda5d2', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '518aa9505fa10ea5662349e5d2efd8c9e32a820b', 'versionType': 'git'}], 'programFiles': ['net/bluetooth/6lowpan.c', 'net/bluetooth/l2cap_core.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.17'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.17', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/bluetooth/6lowpan.c', 'net/bluetooth/l2cap_core.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': 'ba1f1ef6522e63aa5dd29805b4390ea2ccadf05e', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': 'd2a8dc1f619c9e0e4126bee795c39ebddd2ec8ff', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '23a83bac3356e7b211bcdcf581a31f7b536a2c24', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '32c48c7f6cc8c7888e46a8c81622154ccafda5d2', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '518aa9505fa10ea5662349e5d2efd8c9e32a820b', 'versionType': 'git'}], 'programFiles': ['net/bluetooth/6lowpan.c', 'net/bluetooth/l2cap_core.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.17'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.17', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/bluetooth/6lowpan.c', 'net/bluetooth/l2cap_core.c'], 'defaultStatus': 'affected'}] -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 15, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': 'ba1f1ef6522e63aa5dd29805b4390ea2ccadf05e', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': 'd2a8dc1f619c9e0e4126bee795c39ebddd2ec8ff', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '23a83bac3356e7b211bcdcf581a31f7b536a2c24', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '32c48c7f6cc8c7888e46a8c81622154ccafda5d2', 'versionType': 'git'}, {'status': 'affected', 'version': '6b8d4a6a03144c5996f98db7f8256267b0d72a3a', 'lessThan': '518aa9505fa10ea5662349e5d2efd8c9e32a820b', 'versionType': 'git'}], 'programFiles': ['net/bluetooth/6lowpan.c', 'net/bluetooth/l2cap_core.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.17'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.17', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/bluetooth/6lowpan.c', 'net/bluetooth/l2cap_core.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: Bluetooth: 6lowpan: hold L2CAP conn across debugfs control get_l2cap_conn() looks up an LE hci_conn under hdev protection, but then drops that protection before reading hcon->l2cap_data and before lowpan_control_write() later dereferences conn->hcon. A disconnect or device close can tear down the same L2CAP connection in that window. The buggy scenario involves two paths, with each column showing the order within that path: 6LoWPAN control write: HCI disconnect/device close: 1. get_l2cap_conn() finds hcon 1. hci_disconn_cfm() dispatches and hcon->l2cap_data. the L2CAP disconnect callback. 2. get_l2cap_conn() drops hdev 2. l2cap_conn_del() clears protection and returns conn. hcon->l2cap_data and drops the L2CAP connection reference. 3. lowpan_control_write() reads 3. hci_conn_del() removes and drops conn->hcon. the HCI connection. Take a reference to the L2CAP connection with l2cap_conn_hold_unless_zero() while hdev is still locked, and drop that reference after the debugfs command's last use of conn. This mirrors the existing L2CAP ACL receive-side handoff and keeps the connection dereferenceable after leaving hdev protection. Export the existing helper so the bluetooth_6lowpan module can use the same lifetime primitive. Validation reproduced this kernel report: BUG: KASAN: slab-use-after-free in lowpan_control_write+0x374/0x520 The buggy address belongs to the object at ffff888111b9d000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 0 bytes inside of freed 1024-byte region [ffff888111b9d000, ffff888111b9d400) Read of size 8 Call trace: dump_stack_lvl+0x66/0xa0 print_report+0xce/0x5f0 lowpan_control_write+0x374/0x520 (net/bluetooth/6lowpan.c:1131) srso_alias_return_thunk+0x5/0xfbef5 __virt_addr_valid+0x19f/0x330 kasan_report+0xe0/0x110 __debugfs_file_get+0xf7/0x400 full_proxy_write+0x9e/0xd0 vfs_write+0x1b0/0x810 ksys_write+0xd2/0x170 dnotify_flush+0x32/0x220 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x17/0x60 __kasan_kmalloc+0xaa/0xb0 l2cap_conn_add+0x45/0x520 l2cap_chan_connect+0xac6/0xd90 l2cap_sock_connect+0x216/0x350 __sys_connect+0x101/0x130 __x64_sys_connect+0x40/0x50 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x17/0x60 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x313/0x590 hci_conn_hash_flush+0xc0/0x140 hci_dev_close_sync+0x41a/0xb00 hci_dev_close+0x12f/0x160 hci_sock_ioctl+0x157/0x570 sock_do_ioctl+0xf7/0x210 sock_ioctl+0x32f/0x490 __x64_sys_ioctl+0xc7/0x110 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f kasan_record_aux_stack+0xa7/0xc0 insert_work+0x32/0x100 __queue_work+0x262/0xa60 queue_work_on+0xad/0xb0 l2cap_connect_cfm+0x4ef/0x670 hci_le_remote_feat_complete_evt+0x247/0x430 hci_event_packet+0x360/0x6f0 hci_rx_work+0x2ae/0x7a0 process_one_work+0x4fd/0xbc0 worker_thread+0x2d8/0x570 kthread+0x1ad/0x1f0 ret_from_fork+0x3c9/0x540 ret_from_fork_asm+0x1a/0x30 Added Reference https://git.kernel.org/stable/c/23a83bac3356e7b211bcdcf581a31f7b536a2c24 Added Reference https://git.kernel.org/stable/c/32c48c7f6cc8c7888e46a8c81622154ccafda5d2 Added Reference https://git.kernel.org/stable/c/518aa9505fa10ea5662349e5d2efd8c9e32a820b Added Reference https://git.kernel.org/stable/c/ba1f1ef6522e63aa5dd29805b4390ea2ccadf05e Added Reference https://git.kernel.org/stable/c/d2a8dc1f619c9e0e4126bee795c39ebddd2ec8ff