Race condition in Linux Bluetooth ISO queueing causes use-after-free
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 1 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel Bluetooth ISO code adds fragmented packets to a queue without holding its lock, so the transmit worker can dequeue and free a packet that is still being linked. This leads to a use-after-free and queue corruption. A local user who can send data on an ISO socket can trigger it. Affected are Linux kernel versions from 6.0 before the fixed versions listed in the solution.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Serialize fragmented ISO packet queueing The fragmented path in hci_queue_iso() calls __skb_queue_tail() without holding conn->data_q.lock. The socket lock serializes senders, but the transmit worker can concurrently remove packets from this queue using skb_dequeue(). After an insertion saves the old tail pointer, hci_sched_iso() can dequeue that packet and pass it to the driver. The driver can free the packet 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 reported: BUG: KASAN: slab-use-after-free in hci_send_iso+0xc7d/0xe10 Call Trace: hci_send_iso+0xc7d/0xe10 iso_sock_sendmsg+0x710/0x900 __sys_sendto+0x34a/0x3a0 Allocated by task 86: __alloc_skb+0xdd/0x820 alloc_skb_with_frags+0x7e/0x770 sock_alloc_send_pskb+0x67a/0x820 bt_skb_sendmsg.constprop.0+0xc0/0x6c0 iso_sock_sendmsg+0x44e/0x900 Freed by task 90: kmem_cache_free+0xcb/0x3d0 vhci_read+0x33f/0x4d0 vfs_read+0x177/0xa20 Hold the queue lock across the entire fragment batch, as hci_queue_acl() does, to serialize insertion against dequeue while preserving fragment ordering.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Upgrade the Linux kernel to 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10 or 7.3, matching the stable branch in use. The sources list no fixed version for Red Hat Enterprise Linux 10.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98733
- 2026-10-18 Alias added: GHSA-25g3-wm5v-78g8
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-10-21 Fix available: Linux/Linux@545fa70f730eb648a610a2f4b2d270865f77b619, Linux/[email protected] · CNA
- 2026-10-21 1 new reference · CNA
- 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@e328b5823fa6b0b160d0922d6d68323e910d09a4 · CNA
- 2026-10-30 1 new reference · CNA
References
Other 6
- https://git.kernel.org/stable/c/e328b5823fa6b0b160d0922d6d68323e910d09a4
- https://git.kernel.org/stable/c/545fa70f730eb648a610a2f4b2d270865f77b619
- https://git.kernel.org/stable/c/d6d709981208567868c5c01ebd1bec5e5e7fdab0
- https://git.kernel.org/stable/c/708cdd203d0bbcf9255fffb2e4c308d5b28851a7
- https://git.kernel.org/stable/c/a7161730a3ab3f0a3896000db7ab0284683936e6
- https://git.kernel.org/stable/c/1a572db43c057566771b485598ad2e66cb390821
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Sources
- CVE-2026-98733 · CVE Program
- CVE-2026-98733 · NVD
- FIRST EPSS
- GHSA-25g3-wm5v-78g8 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98733 · Red Hat security data · CC BY 4.0
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