{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21969", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.796Z", "datePublished": "2025-04-01T15:47:03.408Z", "dateUpdated": "2026-08-05T11:55:44.372Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:55:44.372Z" }, "descriptions": [ { "lang": "en", "value": "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 \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 \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---" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:A - The vulnerable code is fed by `hci_acldata_packet()` from ACL frames received over the air from a Bluetooth peer, so an attacker within Bluetooth radio range of the target can reach it. Bluetooth is scored as Adjacent per kernel CNA guidance.\nAC:L - The attacker controls both sides of the race — flooding L2CAP signalling frames on one side while inducing the connection abort (BT_CONFIG teardown or `hci_conn_timeout` with refcnt 0) on the other — and the two paths run on separate workqueues (`hdev->workqueue` vs `hdev->req_workqueue`). The window is wide because the RX worker sleeps on `conn->chan_lock` and on `bt_skb_alloc(GFP_KERNEL)` while holding the stale pointer; syzbot reproduced it reliably.\nPR:N - No credentials, pairing, or link-key authentication is required — `hci_acldata_packet()` dispatches straight to `l2cap_recv_acldata()`, and `l2cap_sig_channel()` processes signalling PDUs before any authentication takes place. The `l2cap_conn` is allocated during connection setup in `hci_remote_features_evt`, entirely pre-authentication.\nUI:N - No victim action is needed; the target only has to be connectable, which is the default state for phones, headsets, car kits, and BLE peripherals with Bluetooth enabled. The attacker initiates the ACL connection and drives the entire sequence itself.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed `l2cap_conn` is dereferenced for `hcon`, `hchan`, `rx_skb`, and the `chan_l` channel list, and those pointers are chased into further structures and fed to `hci_send_acl()`. Reclaiming the kmalloc-512 object with sprayed data yields an attacker-directed read primitive and leaks kernel memory.\nI:H - The path performs UAF writes into the freed object (`skb_queue_tail(&conn->pending_rx)`, `conn->rx_len -= len`, `conn->rx_skb = NULL`) and copies attacker-controlled ACL payload through the freed `rx_skb` pointer via `skb_copy_from_linear_data()`. `l2cap_data_channel()` further reaches an indirect `chan->ops->recv()` call through freed memory, giving a control-flow hijack path to arbitrary code execution.\nA:H - The use-after-free reliably oopses the kernel, including taking `mutex_lock()` on a freed mutex and dereferencing freed `hcon`/`hchan` pointers inside a workqueue context. A remote peer can trigger it repeatedly to panic the system." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/l2cap_core.c" ], "versions": [ { "version": "9b3628d79b46f06157affc56fdb218fdd4988321", "lessThan": "c96cce853542b3b13da3738f35ef1be8cfcc9d1d", "status": "affected", "versionType": "git" }, { "version": "9b3628d79b46f06157affc56fdb218fdd4988321", "lessThan": "f8094625a591eeb0b75b1bd9e713fac1d93f5ca9", "status": "affected", "versionType": "git" }, { "version": "9b3628d79b46f06157affc56fdb218fdd4988321", "lessThan": "7790a79c6fce8d5d552bc64f5c82819f719e4f28", "status": "affected", "versionType": "git" }, { "version": "9b3628d79b46f06157affc56fdb218fdd4988321", "lessThan": "b4f82f9ed43aefa79bec2504ae8c29be0c0f5d1d", "status": "affected", "versionType": "git" }, { "version": "995c917d6818b39308ac6baf3f6573cb0486a238", "status": "affected", "versionType": "git" }, { "version": "5.17.14", "lessThan": "5.18", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/l2cap_core.c" ], "versions": [ { "version": "5.18", "status": "affected" }, { "version": "0", "lessThan": "5.18", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.84", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.20", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13.8", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.6.84" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.12.20" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.13.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17.14" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/c96cce853542b3b13da3738f35ef1be8cfcc9d1d" }, { "url": "https://git.kernel.org/stable/c/f8094625a591eeb0b75b1bd9e713fac1d93f5ca9" }, { "url": "https://git.kernel.org/stable/c/7790a79c6fce8d5d552bc64f5c82819f719e4f28" }, { "url": "https://git.kernel.org/stable/c/b4f82f9ed43aefa79bec2504ae8c29be0c0f5d1d" } ], "title": "Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "problemTypes": [ { "descriptions": [ { "type": "CWE", "cweId": "CWE-416", "lang": "en", "description": "CWE-416 Use After Free" } ] } ], "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "timestamp": "2025-10-01T17:15:33.042789Z", "id": "CVE-2025-21969", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T17:15:36.237Z" } } ] } }