CVE-2026-93209
Estado: RecibidaSin puntuar—
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb
BT enable fails intermittently with -ETIMEDOUT (-110). The kernel log shows the HCI Read Local Version command was sent and the firmware replied with status 0x00 (logged by hci_req_cmd_complete() BT_DBG), but the waiter in __hci_cmd_sync_sk() never woke up and timed out after 10 s:
The root cause is that hci_send_cmd_sync() clones the sent command into hdev->req_skb so that hci_req_cmd_complete() can locate the registered completion callback.
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Under memory pressure this skb_clone() fails, leaving hdev->req_skb NULL. The firmware reply is received and processed, but hci_req_cmd_complete() finds NULL req_skb, so hci_cmd_sync_complete() is never called, req_status stays HCI_REQ_PEND, and the waiter times out with -ETIMEDOUT.
req_skb is only used to read bt_cb(skb)->hci callbacks and opcode -- it is never modified. Replace skb_clone() with skb_get(), which simply increments the reference count of hdev->sent_cmd without allocating new memory and therefore cannot fail.
This issue was first observed as a use-after-free in ttyport_close() when ttyport_open() failed, which was investigated in an earlier patch series [1]. That investigation led to the discovery of the true root cause described above.
[1] https://lore.kernel.org/all/20250430111617.1151390-1-quic_cxin@quicinc.com/
Detalles técnicos trazas, registros y código del informe original
bluetooth hci0: Opcode 0xfc00 // __hci_cmd_sync_sk
bluetooth hci0: opcode 0xfc00 plen 1 // hci_cmd_sync_add
bluetooth hci0: skb len 4 // hci_cmd_sync_alloc
bluetooth hci0: length 1 // hci_req_sync_run
Bluetooth: hci0 cmd_cnt 1 cmd queued 1 // hci_cmd_work
Bluetooth: hci0 type 1 len 4 // hci_send_frame
Bluetooth: opcode 0xfc00 status 0x00 // hci_req_cmd_complete
<-- req_skb NULL: req_complete_skb not set,
hci_cmd_sync_complete() never called,
req_status stays HCI_REQ_PEND -->
<-- 10 s later: wait_event_interruptible_timeout expires -->
bluetooth hci0: end: err -110 // __hci_cmd_sync_skCVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.17%
- Percentil entre todas las CVEs puntuadas: 6
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/0337fb092873a4146aa854acb554675b49c8f6b5
- https://git.kernel.org/stable/c/26f66d5b8a5663af498f7ccc94fc79fb47a2191f
- https://git.kernel.org/stable/c/d0b28e9655f4b3195210627577f81883dc1d0162
- https://git.kernel.org/stable/c/d5eef0747071934a1c080ee617fa4fd3566394c5
- https://git.kernel.org/stable/c/d7723320db4c9cb9ec2b9a36140e6c641dd77814
- https://git.kernel.org/stable/c/f5afdff569a09d1cb8cf19826199d024725576cb
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-93209",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
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{
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],
"programFiles": [
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],
"defaultStatus": "unaffected"
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{
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{
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{
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{
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"lessThanOrEqual": "*"
}
],
"programFiles": [
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],
"defaultStatus": "affected"
}
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}
],
"published": "2026-09-24T16:17:15.710",
"references": [
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"url": "https://git.kernel.org/stable/c/0337fb092873a4146aa854acb554675b49c8f6b5",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb\n\nBT enable fails intermittently with -ETIMEDOUT (-110). The kernel log\nshows the HCI Read Local Version command was sent and the firmware\nreplied with status 0x00 (logged by hci_req_cmd_complete() BT_DBG),\nbut the waiter in __hci_cmd_sync_sk() never woke up and timed out\nafter 10 s:\n\n bluetooth hci0: Opcode 0xfc00 // __hci_cmd_sync_sk\n bluetooth hci0: opcode 0xfc00 plen 1 // hci_cmd_sync_add\n bluetooth hci0: skb len 4 // hci_cmd_sync_alloc\n bluetooth hci0: length 1 // hci_req_sync_run\n Bluetooth: hci0 cmd_cnt 1 cmd queued 1 // hci_cmd_work\n Bluetooth: hci0 type 1 len 4 // hci_send_frame\n Bluetooth: opcode 0xfc00 status 0x00 // hci_req_cmd_complete\n <-- req_skb NULL: req_complete_skb not set,\n hci_cmd_sync_complete() never called,\n req_status stays HCI_REQ_PEND -->\n <-- 10 s later: wait_event_interruptible_timeout expires -->\n bluetooth hci0: end: err -110 // __hci_cmd_sync_sk\n\nThe root cause is that hci_send_cmd_sync() clones the sent command\ninto hdev->req_skb so that hci_req_cmd_complete() can locate the\nregistered completion callback. Under memory pressure this\nskb_clone() fails, leaving hdev->req_skb NULL. The firmware reply\nis received and processed, but hci_req_cmd_complete() finds NULL\nreq_skb, so hci_cmd_sync_complete() is never called, req_status\nstays HCI_REQ_PEND, and the waiter times out with -ETIMEDOUT.\n\nreq_skb is only used to read bt_cb(skb)->hci callbacks and opcode --\nit is never modified. Replace skb_clone() with skb_get(), which\nsimply increments the reference count of hdev->sent_cmd without\nallocating new memory and therefore cannot fail.\n\nThis issue was first observed as a use-after-free in ttyport_close()\nwhen ttyport_open() failed, which was investigated in an earlier\npatch series [1]. That investigation led to the discovery of the\ntrue root cause described above.\n\n[1] https://lore.kernel.org/all/20250430111617.1151390-1-quic_cxin@quicinc.com/"
}
],
"lastModified": "2026-09-24T16:17:15.710",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}