CVE-2026-64434 (GCVE-0-2026-64434)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-08-19 16:28
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref
l2cap_chan_timeout() runs asynchronously and accesses chan->conn. If
the connection is torn down while the timer is running or pending,
chan->conn can be freed, leading to a use-after-free when the timer
worker attempts to lock conn->lock:
| BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]
| BUG: KASAN: slab-use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]
| BUG: KASAN: slab-use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]
| BUG: KASAN: slab-use-after-free in mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318
| Write of size 8 at addr ffff8881298d9550 by task kworker/2:1/83
|
| CPU: 2 UID: 0 PID: 83 Comm: kworker/2:1 Not tainted 7.1.0-rc6-next-20260601-dirty #6 PREEMPT(full)
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
| Workqueue: events l2cap_chan_timeout
| Call Trace:
| <TASK>
| instrument_atomic_read_write include/linux/instrumented.h:112 [inline]
| atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]
| __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]
| mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318
| l2cap_chan_timeout+0x5d/0x1b0 net/bluetooth/l2cap_core.c:422
| process_one_work kernel/workqueue.c:3326 [inline]
| process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409
| worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490
| kthread+0x346/0x430 kernel/kthread.c:436
| ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158
| ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
| </TASK>
|
| Allocated by task 320:
| l2cap_conn_add+0xa7/0x820 net/bluetooth/l2cap_core.c:7075
| l2cap_connect_cfm+0xdb/0xd70 net/bluetooth/l2cap_core.c:7452
| hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]
| hci_remote_features_evt+0x52f/0x9f0 net/bluetooth/hci_event.c:3760
| hci_event_func net/bluetooth/hci_event.c:7796 [inline]
| hci_event_packet+0x561/0xa70 net/bluetooth/hci_event.c:7847
| hci_rx_work+0x370/0x890 net/bluetooth/hci_core.c:4040
| process_one_work kernel/workqueue.c:3326 [inline]
| process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409
| worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490
| kthread+0x346/0x430 kernel/kthread.c:436
| ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158
| ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
|
| Freed by task 322:
| hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline]
| hci_conn_hash_flush+0x101/0x1f0 net/bluetooth/hci_conn.c:2736
| hci_dev_close_sync+0x889/0xde0 net/bluetooth/hci_sync.c:5405
| hci_dev_do_close net/bluetooth/hci_core.c:502 [inline]
| hci_unregister_dev+0x1f7/0x370 net/bluetooth/hci_core.c:2679
| vhci_release+0x12a/0x180 drivers/bluetooth/hci_vhci.c:690
| __fput+0x369/0x890 fs/file_table.c:510
| task_work_run+0x160/0x1d0 kernel/task_work.c:233
| get_signal+0xf5b/0x1120 kernel/signal.c:2810
| arch_do_signal_or_restart+0x4d/0x600 arch/x86/kernel/signal.c:337
| __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
| exit_to_user_mode_loop+0x85/0x510 kernel/entry/common.c:98
| do_syscall_64+0x263/0x3d0 arch/x86/entry/syscall_64.c:100
| entry_SYSCALL_64_after_hwframe+0x77/0x7f
|
| The buggy address belongs to the object at ffff8881298d9400
| which belongs to the cache kmalloc-512 of size 512
| The buggy address is located 336 bytes inside of
| freed 512-byte region [ffff8881298d9400, ffff8881298d9600)
Fix it by having chan->conn hold a reference to l2cap_conn (via
l2cap_conn_get) when the channel is added to the connection, and
releasing it in the channel destructor. This ensures the l2cap_conn
remains alive as long as the channel exists.
A new FLAG_DEL channel flag is introduced to indicate that the ch
---truncated---
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 3634cbdc2eb414b69ffa752ddbe5e0458518e321 Version: e1c100e2d61bd8c718b7d91fe3e050780a9bf72d Version: deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9 Version: 89dec92041717b027216e110599e4f6d6c921b79 Version: 50dfec218808b148ab4247b1858031b7a32015c5 Version: 859d3ace791ed878ae9ba5522c7844d960da8f88 Version: 8c8e620467a7b51562dbcefbd1f09f288d7d710d Version: 8c8e620467a7b51562dbcefbd1f09f288d7d710d Version: 7555fd885a0603f50e49a655850a1f2bd8a25398 Version: 5.10.259 ≤ Version: 5.15.210 ≤ Version: 6.1.176 ≤ Version: 6.6.143 ≤ Version: 6.12.93 ≤ Version: 6.18.35 ≤ Version: 7.0.12 ≤ |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"include/net/bluetooth/l2cap.h",
"net/bluetooth/l2cap_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "8f90405a4a6f1f1880dc07996b47bf57c712bd8a",
"status": "affected",
"version": "3634cbdc2eb414b69ffa752ddbe5e0458518e321",
"versionType": "git"
},
{
"lessThan": "32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b",
"status": "affected",
"version": "e1c100e2d61bd8c718b7d91fe3e050780a9bf72d",
"versionType": "git"
},
{
"lessThan": "8922c7940bae9ce4b1736dddb6362370793835c2",
"status": "affected",
"version": "deb8493a8fa599f6c95e2465b12bfdfb7f94a1d9",
"versionType": "git"
},
{
"lessThan": "91047a4396a8b1857a6f712a90cf33ec0012b189",
"status": "affected",
"version": "89dec92041717b027216e110599e4f6d6c921b79",
"versionType": "git"
},
{
"lessThan": "0b0e2bf39cf99e458d991b9df253727e036a7d7d",
"status": "affected",
"version": "50dfec218808b148ab4247b1858031b7a32015c5",
"versionType": "git"
},
{
"lessThan": "d3b739db5dc6f688a60d56da872fabaf65246032",
"status": "affected",
"version": "859d3ace791ed878ae9ba5522c7844d960da8f88",
"versionType": "git"
},
{
"lessThan": "50c38d9f42a529691e4e67ea9cedf4f0bfc8d277",
"status": "affected",
"version": "8c8e620467a7b51562dbcefbd1f09f288d7d710d",
"versionType": "git"
},
{
"lessThan": "b66774b48dd98f07254951f74ea6f513efe7ff8b",
"status": "affected",
"version": "8c8e620467a7b51562dbcefbd1f09f288d7d710d",
"versionType": "git"
},
{
"status": "affected",
"version": "7555fd885a0603f50e49a655850a1f2bd8a25398",
"versionType": "git"
},
{
"lessThan": "5.10.265",
"status": "affected",
"version": "5.10.259",
"versionType": "semver"
},
{
"lessThan": "5.15.216",
"status": "affected",
"version": "5.15.210",
"versionType": "semver"
},
{
"lessThan": "6.1.183",
"status": "affected",
"version": "6.1.176",
"versionType": "semver"
},
{
"lessThan": "6.6.145",
"status": "affected",
"version": "6.6.143",
"versionType": "semver"
},
{
"lessThan": "6.12.97",
"status": "affected",
"version": "6.12.93",
"versionType": "semver"
},
{
"lessThan": "6.18.39",
"status": "affected",
"version": "6.18.35",
"versionType": "semver"
},
{
"lessThan": "7.1",
"status": "affected",
"version": "7.0.12",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"include/net/bluetooth/l2cap.h",
"net/bluetooth/l2cap_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"lessThan": "7.1",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.39",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.265",
"versionStartIncluding": "5.10.259",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.216",
"versionStartIncluding": "5.15.210",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.183",
"versionStartIncluding": "6.1.176",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.145",
"versionStartIncluding": "6.6.143",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.97",
"versionStartIncluding": "6.12.93",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.39",
"versionStartIncluding": "6.18.35",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.4",
"versionStartIncluding": "7.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "7.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "7.0.12",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref\n\nl2cap_chan_timeout() runs asynchronously and accesses chan-\u003econn. If\nthe connection is torn down while the timer is running or pending,\nchan-\u003econn can be freed, leading to a use-after-free when the timer\nworker attempts to lock conn-\u003elock:\n\n| BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n| BUG: KASAN: slab-use-after-free in atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n| BUG: KASAN: slab-use-after-free in __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n| BUG: KASAN: slab-use-after-free in mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n| Write of size 8 at addr ffff8881298d9550 by task kworker/2:1/83\n|\n| CPU: 2 UID: 0 PID: 83 Comm: kworker/2:1 Not tainted 7.1.0-rc6-next-20260601-dirty #6 PREEMPT(full)\n| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014\n| Workqueue: events l2cap_chan_timeout\n| Call Trace:\n| \u003cTASK\u003e\n| instrument_atomic_read_write include/linux/instrumented.h:112 [inline]\n| atomic_long_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:4456 [inline]\n| __mutex_trylock_fast kernel/locking/mutex.c:161 [inline]\n| mutex_lock+0x4f/0xa0 kernel/locking/mutex.c:318\n| l2cap_chan_timeout+0x5d/0x1b0 net/bluetooth/l2cap_core.c:422\n| process_one_work kernel/workqueue.c:3326 [inline]\n| process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n| worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n| kthread+0x346/0x430 kernel/kthread.c:436\n| ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n| ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n| \u003c/TASK\u003e\n|\n| Allocated by task 320:\n| l2cap_conn_add+0xa7/0x820 net/bluetooth/l2cap_core.c:7075\n| l2cap_connect_cfm+0xdb/0xd70 net/bluetooth/l2cap_core.c:7452\n| hci_connect_cfm include/net/bluetooth/hci_core.h:2139 [inline]\n| hci_remote_features_evt+0x52f/0x9f0 net/bluetooth/hci_event.c:3760\n| hci_event_func net/bluetooth/hci_event.c:7796 [inline]\n| hci_event_packet+0x561/0xa70 net/bluetooth/hci_event.c:7847\n| hci_rx_work+0x370/0x890 net/bluetooth/hci_core.c:4040\n| process_one_work kernel/workqueue.c:3326 [inline]\n| process_scheduled_works+0x7c8/0xfb0 kernel/workqueue.c:3409\n| worker_thread+0x8a9/0xcf0 kernel/workqueue.c:3490\n| kthread+0x346/0x430 kernel/kthread.c:436\n| ret_from_fork+0x1a3/0x470 arch/x86/kernel/process.c:158\n| ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n|\n| Freed by task 322:\n| hci_disconn_cfm include/net/bluetooth/hci_core.h:2154 [inline]\n| hci_conn_hash_flush+0x101/0x1f0 net/bluetooth/hci_conn.c:2736\n| hci_dev_close_sync+0x889/0xde0 net/bluetooth/hci_sync.c:5405\n| hci_dev_do_close net/bluetooth/hci_core.c:502 [inline]\n| hci_unregister_dev+0x1f7/0x370 net/bluetooth/hci_core.c:2679\n| vhci_release+0x12a/0x180 drivers/bluetooth/hci_vhci.c:690\n| __fput+0x369/0x890 fs/file_table.c:510\n| task_work_run+0x160/0x1d0 kernel/task_work.c:233\n| get_signal+0xf5b/0x1120 kernel/signal.c:2810\n| arch_do_signal_or_restart+0x4d/0x600 arch/x86/kernel/signal.c:337\n| __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]\n| exit_to_user_mode_loop+0x85/0x510 kernel/entry/common.c:98\n| do_syscall_64+0x263/0x3d0 arch/x86/entry/syscall_64.c:100\n| entry_SYSCALL_64_after_hwframe+0x77/0x7f\n|\n| The buggy address belongs to the object at ffff8881298d9400\n| which belongs to the cache kmalloc-512 of size 512\n| The buggy address is located 336 bytes inside of\n| freed 512-byte region [ffff8881298d9400, ffff8881298d9600)\n\nFix it by having chan-\u003econn hold a reference to l2cap_conn (via\nl2cap_conn_get) when the channel is added to the connection, and\nreleasing it in the channel destructor. This ensures the l2cap_conn\nremains alive as long as the channel exists.\n\nA new FLAG_DEL channel flag is introduced to indicate that the ch\n---truncated---"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:A - An unauthenticated Bluetooth peer within radio range can reach the vulnerable worker by creating a half-configured L2CAP channel and subsequently terminating the ACL connection.\nAC:L - The attacker controls both channel creation and connection teardown, can leave the 40-second channel timer armed, and can repeat or parallelize attempts to win the race.\nPR:N - The BR/EDR signaling path processes incoming L2CAP requests before application acceptance, and an SDP listener permits this path without pairing or authentication.\nUI:N - Exploitation requires no victim action because an already-running Bluetooth service and the kernel independently process the connection, timer, and disconnection.\nS:U - The UAF compromises the host kernel within the same security authority and does not inherently cross a VM, IOMMU, or comparable boundary.\nC:H - The freed kmalloc object can be reclaimed with attacker-influenced contents, allowing the UAF to support kernel-memory disclosure primitives.\nI:H - The worker performs mutex writes into the freed allocation, enabling heap corruption and potentially arbitrary write or kernel control-flow hijacking after heap grooming.\nA:H - The stale mutex access can corrupt memory, trigger an oops or panic, and can be retriggered by a nearby Bluetooth peer."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:28:16.061Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/8f90405a4a6f1f1880dc07996b47bf57c712bd8a"
},
{
"url": "https://git.kernel.org/stable/c/32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b"
},
{
"url": "https://git.kernel.org/stable/c/8922c7940bae9ce4b1736dddb6362370793835c2"
},
{
"url": "https://git.kernel.org/stable/c/91047a4396a8b1857a6f712a90cf33ec0012b189"
},
{
"url": "https://git.kernel.org/stable/c/0b0e2bf39cf99e458d991b9df253727e036a7d7d"
},
{
"url": "https://git.kernel.org/stable/c/d3b739db5dc6f688a60d56da872fabaf65246032"
},
{
"url": "https://git.kernel.org/stable/c/50c38d9f42a529691e4e67ea9cedf4f0bfc8d277"
},
{
"url": "https://git.kernel.org/stable/c/b66774b48dd98f07254951f74ea6f513efe7ff8b"
}
],
"title": "Bluetooth: L2CAP: Fix UAF in channel timeout by holding conn ref",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-64434",
"datePublished": "2026-07-25T08:51:09.066Z",
"dateReserved": "2026-07-19T15:36:31.787Z",
"dateUpdated": "2026-08-19T16:28:16.061Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…