VulnerabilityPublished 18 Oct 2026

CVE-2026-98733: Linux kernel · Bluetooth: hci_core: Serialize fragmented ISO packet queueing

Source GCVE Database

Authoritative record:CVE-2026-98733

Not known to be exploited · fixed in d6d709981208567868c5c01ebd1bec5e5e7fdab0 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

Severity

High

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 d6d709981208567868c5c01ebd1bec5e5e7fdab0, a7161730a3ab3f0a3896000db7ab0284683936e6, 708cdd203d0bbcf9255fffb2e4c308d5b28851a7 +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.

ghsa-25g3-wm5v-78g8

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 26afbd826ee326e63a334c37fd45e82e50a615ec, < d6d709981208567868c5c01ebd1bec5e5e7fdab0	Fixed in d6d709981208567868c5c01ebd1bec5e5e7fdab0
LinuxLinux	Affected ≥ 26afbd826ee326e63a334c37fd45e82e50a615ec, < a7161730a3ab3f0a3896000db7ab0284683936e6	Fixed in a7161730a3ab3f0a3896000db7ab0284683936e6
LinuxLinux	Affected ≥ 26afbd826ee326e63a334c37fd45e82e50a615ec, < 708cdd203d0bbcf9255fffb2e4c308d5b28851a7	Fixed in 708cdd203d0bbcf9255fffb2e4c308d5b28851a7
LinuxLinux	Affected ≥ 26afbd826ee326e63a334c37fd45e82e50a615ec, < 545fa70f730eb648a610a2f4b2d270865f77b619	Fixed in 545fa70f730eb648a610a2f4b2d270865f77b619
LinuxLinux	Affected ≥ 26afbd826ee326e63a334c37fd45e82e50a615ec, < 1a572db43c057566771b485598ad2e66cb390821	Fixed in 1a572db43c057566771b485598ad2e66cb390821
LinuxLinux	Affected =6.0	Fixed in–

AI-suggested

The described fix involves holding the queue lock during the entire fragment batch insertion to prevent concurrent queue modifications and use-after-free.

Description

A use-after-free vulnerability in the Linux kernel's Bluetooth hci_core component was resolved. The issue arises from improper serialization of fragmented ISO packet queueing, where concurrent access to the packet queue can lead to memory corruption and use-after-free conditions. This flaw was detected by KASAN and involves the hci_queue_iso() and hci_sched_iso() functions. The fix involves holding the queue lock across the entire fragment batch to prevent concurrent modifications.

Impact

The vulnerability can cause use-after-free conditions and queue corruption in the Bluetooth ISO packet queueing path of the Linux kernel. This can lead to memory corruption, potentially causing kernel crashes or undefined behavior. No known exploits in the wild have been reported.

Summary

The vulnerability in the Linux kernel Bluetooth hci_core subsystem involves the fragmented path in hci_queue_iso() calling __skb_queue_tail() without holding the conn->data_q.lock. While the socket lock serializes senders, the transmit worker can concurrently dequeue packets using skb_dequeue(). This concurrency allows hci_sched_iso() to dequeue and pass a packet to the driver, which may free it before the insertion resumes and writes to the old tail's next pointer, causing a use-after-free. Concurrent updates can also corrupt the queue. KASAN detected a slab-use-after-free in hci_send_iso. The resolution is to hold the queue lock across the entire fragment batch, similar to hci_queue_acl(), to serialize insertion against dequeue and preserve fragment ordering.

References

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