CVE-2026-98735
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_core: Serialize ACL scheduling with channel deletion
hci_chan_sent() selects a channel under RCU but drops the read lock before accessing chan->conn and returning the channel. The ACL and LE schedulers then use its packet queue and update its transmit counters without any protection against channel deletion.
After TX selects a channel and releases RCU, a disconnect command timeout on the separate request workqueue can run hci_conn_failed() and l2cap_conn_del(). hci_chan_del() can then unlink the channel, complete synchronize_rcu(), purge its queue and free it before TX resumes. This causes use-after-free both in hci_chan_sent() and in its callers.
Read full descriptionShow less
Hold the existing device mutex across channel selection and transmission in both schedulers to serialize them with channel teardown. Keep timeout handling outside the critical sections because hci_link_tx_to() acquires the same mutex. This also permits the transmit path to sleep, unlike extending the RCU read-side critical section across packet submission.
Technical details traces, logs and code from the original report
KASAN reported: BUG: KASAN: slab-use-after-free in hci_chan_sent+0x892/0x9b0 Workqueue: hci0 hci_tx_work Call Trace: hci_chan_sent+0x892/0x9b0 hci_tx_work+0x5e6/0xb70 Allocated by task 91: hci_chan_create+0xe3/0x350 l2cap_conn_add.part.0+0x12/0xa30 l2cap_chan_connect+0x110d/0x1b60 l2cap_sock_connect+0x310/0x530 Freed by task 99: hci_chan_del+0x11f/0x170 l2cap_conn_del+0x4f1/0x800 l2cap_connect_cfm+0x88c/0xd30 hci_conn_failed+0x150/0x250 hci_abort_conn_sync+0x3e3/0x800 hci_cmd_sync_run+0x7e/0xc0 hci_abort_conn+0x105/0x1f0 disconnect_sync+0x157/0x290 hci_cmd_sync_work+0x13c/0x290
CVSS
NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.17 %
- Percentile among all scored CVEs
- 6
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
References
Show 4 references
Raw JSON (NVD)
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{
"id": "CVE-2026-98735",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3eff45eaf81780dad25c167bbaafa7d25ae407da",
"lessThan": "51f95ea451f25d7e3f048c0f438f04fa74688aae",
"versionType": "git"
},
{
"status": "affected",
"version": "3eff45eaf81780dad25c167bbaafa7d25ae407da",
"lessThan": "86e9708f9d19a7f1bd5dc9c1652d07707f79f5bd",
"versionType": "git"
},
{
"status": "affected",
"version": "3eff45eaf81780dad25c167bbaafa7d25ae407da",
"lessThan": "4fda8f0abeea9929036446d89a476fb8298abcb0",
"versionType": "git"
},
{
"status": "affected",
"version": "3eff45eaf81780dad25c167bbaafa7d25ae407da",
"lessThan": "f4845ab191a4f686a5da481fbba90ed73bb693b0",
"versionType": "git"
}
],
"programFiles": [
"net/bluetooth/hci_core.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.3"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.3",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.113",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.56",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/bluetooth/hci_core.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:27.127",
"references": [
{
"url": "https://git.kernel.org/stable/c/4fda8f0abeea9929036446d89a476fb8298abcb0",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/51f95ea451f25d7e3f048c0f438f04fa74688aae",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/86e9708f9d19a7f1bd5dc9c1652d07707f79f5bd",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f4845ab191a4f686a5da481fbba90ed73bb693b0",
"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: Serialize ACL scheduling with channel deletion\n\nhci_chan_sent() selects a channel under RCU but drops the read lock before\naccessing chan->conn and returning the channel. The ACL and LE schedulers\nthen use its packet queue and update its transmit counters without any\nprotection against channel deletion.\n\nAfter TX selects a channel and releases RCU, a disconnect command timeout\non the separate request workqueue can run hci_conn_failed() and\nl2cap_conn_del(). hci_chan_del() can then unlink the channel, complete\nsynchronize_rcu(), purge its queue and free it before TX resumes. This\ncauses use-after-free both in hci_chan_sent() and in its callers.\n\nKASAN reported:\n\n BUG: KASAN: slab-use-after-free in hci_chan_sent+0x892/0x9b0\n Workqueue: hci0 hci_tx_work\n Call Trace:\n hci_chan_sent+0x892/0x9b0\n hci_tx_work+0x5e6/0xb70\n Allocated by task 91:\n hci_chan_create+0xe3/0x350\n l2cap_conn_add.part.0+0x12/0xa30\n l2cap_chan_connect+0x110d/0x1b60\n l2cap_sock_connect+0x310/0x530\n Freed by task 99:\n hci_chan_del+0x11f/0x170\n l2cap_conn_del+0x4f1/0x800\n l2cap_connect_cfm+0x88c/0xd30\n hci_conn_failed+0x150/0x250\n hci_abort_conn_sync+0x3e3/0x800\n hci_cmd_sync_run+0x7e/0xc0\n hci_abort_conn+0x105/0x1f0\n disconnect_sync+0x157/0x290\n hci_cmd_sync_work+0x13c/0x290\n\nHold the existing device mutex across channel selection and transmission\nin both schedulers to serialize them with channel teardown. Keep timeout\nhandling outside the critical sections because hci_link_tx_to() acquires\nthe same mutex. This also permits the transmit path to sleep, unlike\nextending the RCU read-side critical section across packet submission."
}
],
"lastModified": "2026-10-19T10:19:37.633",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}