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CVE-2025-21969— Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd

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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于Bluetooth L2CAP模块在l2cap_send_cmd中存在slab释放后读取问题。

CVSS 8.8 · High EPSS 0.23% · P13 Updated Aug 05, 2026

Possible ATT&CK Techniques 2 AI

T1059 · Command and Scripting Interpreter T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 12

Vendor	Product	Version Range	Status
Linux	Linux	`9b3628d79b46f06157affc56fdb218fdd4988321< c96cce853542b3b13da3738f35ef1be8cfcc9d1d`	affected
		`9b3628d79b46f06157affc56fdb218fdd4988321< f8094625a591eeb0b75b1bd9e713fac1d93f5ca9`	affected
		`9b3628d79b46f06157affc56fdb218fdd4988321< 7790a79c6fce8d5d552bc64f5c82819f719e4f28`	affected
		`9b3628d79b46f06157affc56fdb218fdd4988321< b4f82f9ed43aefa79bec2504ae8c29be0c0f5d1d`	affected
		`995c917d6818b39308ac6baf3f6573cb0486a238`	affected
		`5.17.14< 5.18`	affected
		`5.18`	affected
		`< 5.18`	unaffected
… +4 more rows

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I. Basic Information for CVE-2025-21969

Vulnerability Information

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Vulnerability Title

Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd

Source: CVE Program / CVE List V5

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd After the hci sync command releases l2cap_conn, the hci receive data work queue references the released l2cap_conn when sending to the upper layer. Add hci dev lock to the hci receive data work queue to synchronize the two. [1] BUG: KASAN: slab-use-after-free in l2cap_send_cmd+0x187/0x8d0 net/bluetooth/l2cap_core.c:954 Read of size 8 at addr ffff8880271a4000 by task kworker/u9:2/5837 CPU: 0 UID: 0 PID: 5837 Comm: kworker/u9:2 Not tainted 6.13.0-rc5-syzkaller-00163-gab75170520d4 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: hci1 hci_rx_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x169/0x550 mm/kasan/report.c:489 kasan_report+0x143/0x180 mm/kasan/report.c:602 l2cap_build_cmd net/bluetooth/l2cap_core.c:2964 [inline] l2cap_send_cmd+0x187/0x8d0 net/bluetooth/l2cap_core.c:954 l2cap_sig_send_rej net/bluetooth/l2cap_core.c:5502 [inline] l2cap_sig_channel net/bluetooth/l2cap_core.c:5538 [inline] l2cap_recv_frame+0x221f/0x10db0 net/bluetooth/l2cap_core.c:6817 hci_acldata_packet net/bluetooth/hci_core.c:3797 [inline] hci_rx_work+0x508/0xdb0 net/bluetooth/hci_core.c:4040 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> Allocated by task 5837: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4329 kmalloc_noprof include/linux/slab.h:901 [inline] kzalloc_noprof include/linux/slab.h:1037 [inline] l2cap_conn_add+0xa9/0x8e0 net/bluetooth/l2cap_core.c:6860 l2cap_connect_cfm+0x115/0x1090 net/bluetooth/l2cap_core.c:7239 hci_connect_cfm include/net/bluetooth/hci_core.h:2057 [inline] hci_remote_features_evt+0x68e/0xac0 net/bluetooth/hci_event.c:3726 hci_event_func net/bluetooth/hci_event.c:7473 [inline] hci_event_packet+0xac2/0x1540 net/bluetooth/hci_event.c:7525 hci_rx_work+0x3f3/0xdb0 net/bluetooth/hci_core.c:4035 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Freed by task 54: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:582 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2353 [inline] slab_free mm/slub.c:4613 [inline] kfree+0x196/0x430 mm/slub.c:4761 l2cap_connect_cfm+0xcc/0x1090 net/bluetooth/l2cap_core.c:7235 hci_connect_cfm include/net/bluetooth/hci_core.h:2057 [inline] hci_conn_failed+0x287/0x400 net/bluetooth/hci_conn.c:1266 hci_abort_conn_sync+0x56c/0x11f0 net/bluetooth/hci_sync.c:5603 hci_cmd_sync_work+0x22b/0x400 net/bluetooth/hci_sync.c:332 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr ---truncated---

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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

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	9b3628d79b46f06157affc56fdb218fdd4988321 ~ c96cce853542b3b13da3738f35ef1be8cfcc9d1d	-
Linux	Linux	5.18	-

II. Public POCs for CVE-2025-21969

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2025-21969

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Patches & Fixes for CVE-2025-21969 (2)

https://www.cve.org/CVERecord?id=CVE-2025-21969

Same Patch Batch · Linux · 2025-04-01 · 93 CVEs total

CVE-2025-21954	9.8 CRITICAL	netmem: prevent TX of unreadable skbs
CVE-2025-21927	9.8 CRITICAL	nvme-tcp: fix potential memory corruption in nvme_tcp_recv_pdu()
CVE-2025-21955	8.8 HIGH	ksmbd: prevent connection release during oplock break notification
CVE-2025-21946	8.8 HIGH	ksmbd: fix out-of-bounds in parse_sec_desc()
CVE-2025-21945	8.8 HIGH	ksmbd: fix use-after-free in smb2_lock
CVE-2025-21967	8.8 HIGH	ksmbd: fix use-after-free in ksmbd_free_work_struct
CVE-2025-21972	8.8 HIGH	net: mctp: unshare packets when reassembling
CVE-2025-21947	8.1 HIGH	ksmbd: fix type confusion via race condition when using ipc_msg_send_request
CVE-2025-21971	7.8 HIGH	net_sched: Prevent creation of classes with TC_H_ROOT
CVE-2025-21970	7.8 HIGH	net/mlx5: Bridge, fix the crash caused by LAG state check
CVE-2025-21899	7.8 HIGH	tracing: Fix bad hist from corrupting named_triggers list
CVE-2025-21979	7.8 HIGH	wifi: cfg80211: cancel wiphy_work before freeing wiphy
CVE-2025-21901	7.8 HIGH	RDMA/bnxt_re: Add sanity checks on rdev validity
CVE-2025-21926	7.8 HIGH	net: gso: fix ownership in __udp_gso_segment
CVE-2025-21966	7.8 HIGH	dm-flakey: Fix memory corruption in optional corrupt_bio_byte feature
CVE-2025-21965	7.8 HIGH	sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()
CVE-2025-21934	7.8 HIGH	rapidio: fix an API misues when rio_add_net() fails
CVE-2025-21939	7.8 HIGH	drm/xe/hmm: Don't dereference struct page pointers without notifier lock
CVE-2025-21958	7.8 HIGH	Revert "openvswitch: switch to per-action label counting in conntrack"
CVE-2025-21949	7.8 HIGH	LoongArch: Set hugetlb mmap base address aligned with pmd size

Showing top 20 of 93 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux

Same vendor: Linux