VulnerabilityPublished 18 Oct 2026Updated 21 Oct 2026

CVE-2026-98734: Linux kernel · Bluetooth: hci_core: Serialize SCO and ISO scheduling with teardown

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f997e03e2ef58aa7114828c9d924e515a9a1db9c : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:18 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f997e03e2ef58aa7114828c9d924e515a9a1db9c, ecdb1c66d8e14e63731c52d6fbcfa604064913c4, 101825c09ad6b7daa6cf4c9e6b1720b13de15596 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ bf4c63252490ba78fb833cc7acf1a5b1900c970f, < f997e03e2ef58aa7114828c9d924e515a9a1db9c	Fixed in f997e03e2ef58aa7114828c9d924e515a9a1db9c
LinuxLinux	Affected ≥ bf4c63252490ba78fb833cc7acf1a5b1900c970f, < ecdb1c66d8e14e63731c52d6fbcfa604064913c4	Fixed in ecdb1c66d8e14e63731c52d6fbcfa604064913c4
LinuxLinux	Affected ≥ bf4c63252490ba78fb833cc7acf1a5b1900c970f, < 101825c09ad6b7daa6cf4c9e6b1720b13de15596	Fixed in 101825c09ad6b7daa6cf4c9e6b1720b13de15596
LinuxLinux	Affected ≥ bf4c63252490ba78fb833cc7acf1a5b1900c970f, < 1681f97afdf92e8557f2f3118ddc898471b5d299	Fixed in 1681f97afdf92e8557f2f3118ddc898471b5d299
LinuxLinux	Affected ≥ bf4c63252490ba78fb833cc7acf1a5b1900c970f, < 848a7a91c7f03675d3bd8db6f7721cbf9cb50e21	Fixed in 848a7a91c7f03675d3bd8db6f7721cbf9cb50e21
LinuxLinux	Affected =3.3	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Serialize SCO and ISO scheduling with teardown hci_low_sent() selects a connection under RCU but drops the read lock before calculating its quota and returning it to the scheduler. The connection is then used without lifetime protection by hci_sched_iso() and hci_sched_sco(). After the TX worker drops the RCU read lock, hci_abort_conn_sync() on hdev->req_workqueue can remove the connection from the hash, complete synchronize_rcu(), purge its queues and release it. The TX worker on hdev->workqueue can then access the freed connection in hci_quote_sent() or while dequeuing packets and updating conn->sent. KASAN reported: BUG: KASAN: slab-use-after-free in hci_low_sent+0x730/0x840 Workqueue: hci0 hci_tx_work Call Trace: hci_low_sent+0x730/0x840 hci_sched_iso+0x25e/0x4d0 hci_tx_work+0x239/0xcb0 Allocated by task 93: __hci_conn_add+0x16f/0x1b40 hci_bind_bis+0x782/0x17b0 hci_connect_bis+0xa0/0x510 iso_sock_connect+0x589/0x1050 Freed by task 88: kfree+0x131/0x3c0 device_release+0xc8/0x240 kobject_put+0x14d/0x280 hci_conn_del+0x55a/0xe80 hci_disconnect_sync+0x156/0x180 hci_abort_conn_sync+0x3e7/0x940 hci_cmd_sync_work+0x13c/0x290 Hold hci_dev_lock() across connection selection and transmission in both SCO and ISO scheduling, serializing them with connection teardown. This also prevents queuing completion timestamps after the connection queues have been purged. Extending RCU across transmission would be unsafe because the transmit path can sleep. Keep the ISO timeout check outside the mutex since hci_link_tx_to() takes it itself. The preceding channel fix already holds this mutex in the ACL and LE schedulers, which call the SCO scheduler between packets. Move the SCO body to __hci_sched_sco(), assert that its caller holds the mutex, and use it directly from these locked paths. Keep a locking hci_sched_sco() wrapper for the direct calls from hci_tx_work(). This avoids recursively acquiring the device mutex while preserving the scheduling order. Remove the obsolete claim that connection removal disables TX.

References

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