{"cve":"CVE-2025-21969","nvd":{"published":"2025-04-01T16:15:28.207","modified":"2026-10-30T13:17:55.237","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd\n\nAfter the hci sync command releases l2cap_conn, the hci receive data work\nqueue references the released l2cap_conn when sending to the upper layer.\nAdd hci dev lock to the hci receive data work queue to synchronize the two.\n\n[1]\nBUG: KASAN: slab-use-after-free in l2cap_send_cmd+0x187/0x8d0 net/bluetooth/l2cap_core.c:954\nRead of size 8 at addr ffff8880271a4000 by task kworker/u9:2/5837\n\nCPU: 0 UID: 0 PID: 5837 Comm: kworker/u9:2 Not tainted 6.13.0-rc5-syzkaller-00163-gab75170520d4 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\nWorkqueue: hci1 hci_rx_work\nCall Trace:\n <TASK>\n __dump_stack lib/dump_stack.c:94 [inline]\n dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378 [inline]\n print_report+0x169/0x550 mm/kasan/report.c:489\n kasan_report+0x143/0x180 mm/kasan/report.c:602\n l2cap_build_cmd net/bluetooth/l2cap_core.c:2964 [inline]\n l2cap_send_cmd+0x187/0x8d0 net/bluetooth/l2cap_core.c:954\n l2cap_sig_send_rej net/bluetooth/l2cap_core.c:5502 [inline]\n l2cap_sig_channel net/bluetooth/l2cap_core.c:5538 [inline]\n l2cap_recv_frame+0x221f/0x10db0 net/bluetooth/l2cap_core.c:6817\n hci_acldata_packet net/bluetooth/hci_core.c:3797 [inline]\n hci_rx_work+0x508/0xdb0 net/bluetooth/hci_core.c:4040\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f0/0x390 kernel/kthread.c:389\n ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n </TASK>\n\nAllocated by task 5837:\n kasan_save_stack mm/kasan/common.c:47 [inline]\n kasan_save_track+0x3f/0x80 mm/kasan/common.c:68\n poison_kmalloc_redzone mm/kasan/common.c:377 [inline]\n __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394\n kasan_kmalloc include/linux/kasan.h:260 [inline]\n __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4329\n kmalloc_noprof include/linux/slab.h:901 [inline]\n kzalloc_noprof include/linux/slab.h:1037 [inline]\n l2cap_conn_add+0xa9/0x8e0 net/bluetooth/l2cap_core.c:6860\n l2cap_connect_cfm+0x115/0x1090 net/bluetooth/l2cap_core.c:7239\n hci_connect_cfm include/net/bluetooth/hci_core.h:2057 [inline]\n hci_remote_features_evt+0x68e/0xac0 net/bluetooth/hci_event.c:3726\n hci_event_func net/bluetooth/hci_event.c:7473 [inline]\n hci_event_packet+0xac2/0x1540 net/bluetooth/hci_event.c:7525\n hci_rx_work+0x3f3/0xdb0 net/bluetooth/hci_core.c:4035\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f0/0x390 kernel/kthread.c:389\n ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n\nFreed by task 54:\n kasan_save_stack mm/kasan/common.c:47 [inline]\n kasan_save_track+0x3f/0x80 mm/kasan/common.c:68\n kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:582\n poison_slab_object mm/kasan/common.c:247 [inline]\n __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264\n kasan_slab_free include/linux/kasan.h:233 [inline]\n slab_free_hook mm/slub.c:2353 [inline]\n slab_free mm/slub.c:4613 [inline]\n kfree+0x196/0x430 mm/slub.c:4761\n l2cap_connect_cfm+0xcc/0x1090 net/bluetooth/l2cap_core.c:7235\n hci_connect_cfm include/net/bluetooth/hci_core.h:2057 [inline]\n hci_conn_failed+0x287/0x400 net/bluetooth/hci_conn.c:1266\n hci_abort_conn_sync+0x56c/0x11f0 net/bluetooth/hci_sync.c:5603\n hci_cmd_sync_work+0x22b/0x400 net/bluetooth/hci_sync.c:332\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f0/0x390 kernel/kthread.c:389\n ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr\n---truncated---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/7790a79c6fce8d5d552bc64f5c82819f719e4f28","https://git.kernel.org/stable/c/967473b1e8bb6d941e034ec1f76de40ccf54a8cf","https://git.kernel.org/stable/c/b4f82f9ed43aefa79bec2504ae8c29be0c0f5d1d","https://git.kernel.org/stable/c/c96cce853542b3b13da3738f35ef1be8cfcc9d1d","https://git.kernel.org/stable/c/f8094625a591eeb0b75b1bd9e713fac1d93f5ca9"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-30T13:47:47.119061695+00:00"},"epss":{"cve":"CVE-2025-21969","score":0.0023,"percentile":0.139,"date":"2026-10-30"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}