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CVE-2026-72336— Bluetooth: 6lowpan: hold L2CAP conn across debugfs control

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于get_l2cap_conn()函数在释放hdev保护后仍使用L2CAP连接对象，可能导致释放后重用。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.20% · P10

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 6b8d4a6a03144c5996f98db7f8256267b0d72a3a< ba1f1ef6522e63aa5dd29805b4390ea2ccadf05e affected
6b8d4a6a03144c5996f98db7f8256267b0d72a3a< d2a8dc1f619c9e0e4126bee795c39ebddd2ec8ff affected
6b8d4a6a03144c5996f98db7f8256267b0d72a3a< 23a83bac3356e7b211bcdcf581a31f7b536a2c24 affected
6b8d4a6a03144c5996f98db7f8256267b0d72a3a< 32c48c7f6cc8c7888e46a8c81622154ccafda5d2 affected
6b8d4a6a03144c5996f98db7f8256267b0d72a3a< 518aa9505fa10ea5662349e5d2efd8c9e32a820b affected
3.17 affected
< 3.17 unaffected
6.6.145≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-72336

Vulnerability Information
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Vulnerability Title
Bluetooth: 6lowpan: hold L2CAP conn across debugfs control
Source: CVE Program / CVE List V5
Vulnerability 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
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于get_l2cap_conn()函数在释放hdev保护后仍使用L2CAP连接对象，可能导致释放后重用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 6b8d4a6a03144c5996f98db7f8256267b0d72a3a ~ ba1f1ef6522e63aa5dd29805b4390ea2ccadf05e -
Linux Linux 3.17 -

II. Public POCs for CVE-2026-72336

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III. Intelligence Information for CVE-2026-72336

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Patches & Fixes for CVE-2026-72336 (5)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72463 9.8 CRITICAL xfrm: Fix dev use-after-free in xfrm async resumption
CVE-2026-72248 9.8 CRITICAL netfilter: flowtable: support IPIP tunnel with direct xmit
CVE-2026-72381 9.8 CRITICAL ksmbd: fix use-after-free of fp->owner.name in durable handle owner check
CVE-2026-72477 9.8 CRITICAL fs/ntfs3: call _ntfs_bad_inode() when failing to rename
CVE-2026-72473 9.8 CRITICAL xprtrdma: Decouple req recycling from RPC completion
CVE-2026-72472 9.8 CRITICAL nfs: use nfsi->rwsem to protect traversal of the file lock list
CVE-2026-74406 9.8 CRITICAL vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().
CVE-2026-72222 9.8 CRITICAL sunrpc: pin svc_xprt across the asynchronous TLS handshake callback
CVE-2026-72226 9.8 CRITICAL batman-adv: tt: prevent TVLV OOB check overflow
CVE-2026-72137 9.8 CRITICAL xfrm: nat_keepalive: avoid double free on send error
CVE-2026-74376 9.8 CRITICAL md/raid10: reset read_slot when reusing r10bio for discard
CVE-2026-72130 9.8 CRITICAL nvmet-auth: reject short AUTH_RECEIVE buffers

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-72336

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