CVE-2026-99011: Linux Vulnerability (CVSS 7.1)

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata() sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a strong reference under hdev->lock: hci_dev_lock(hdev); hcon = hci_conn_hash_lookup_handle(hdev, handle); ... conn = sco_conn_hold_unless_zero(hcon->sco_data); hci_dev_unlock(hdev); but the pointer is cleared from the other side without that lock. When the last sco_conn reference is dropped, sco_conn_free() ran conn->hcon->sco_data = NULL; with no hdev->lock held, so the RX path could read hcon->sco_data and call kref_get_unless_zero() on an sco_conn that was concurrently freed: BUG: KASAN: slab-use-after-free in sco_conn_hold_unless_zero+0xbe/0x160 Write of size 4 by task kworker/u17:0 Workqueue: hci0 hci_rx_work Call Trace: sco_conn_hold_unless_zero+0xbe/0x160 sco_recv_scodata+0x13f/0x490 hci_rx_work+0x3af/0x730 kref_get_unless_zero() only guards against a zero refcount, not against the backing memory already being freed. Give hcon->sco_data an actual reference on the sco_conn it points to, so the object cannot be freed while the pointer is still installed, and only clear and drop it from sco_conn_del(), which runs under hdev->lock (its callers, sco_connect_cfm() and sco_disconn_cfm(), hold it). The reader in sco_recv_scodata() also takes hdev->lock, so the store and the read are now serialised: the RX path either observes NULL or a reference that is guaranteed to stay valid until it drops its own. sco_conn_add() no longer hands its kref_init() reference to the caller as the connection's only reference; that initial reference is the one owned by hcon->sco_data, and callers get their own via sco_conn_hold(). Because the sco_conn can now outlive the socket (the association keeps it alive until the link goes down), the hci_conn can no longer be dropped from sco_conn_free() without regressing socket close: closing a connected SCO socket must still tear the link down. Move hci_conn ownership to the socket instead: __sco_chan_add() takes an hci_conn reference and it is released from sco_chan_del() and sco_sock_destruct(), exactly once. The sco_conn no longer owns an hci_conn reference, so sco_conn_add() stops consuming one and sco_connect() drops the hci_connect_sco() reference on every path; sco_connect_cfm() no longer needs its hci_conn_hold() dance.

Metrics

CVSS 3.1

7.1/10

CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= e6720779ae612a14ac4ba7fe4fd5b27d900d932c, < b108ea7ebba147465f4158d8133f0e8f013762ed; >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c, < 8a98d58f6cfe70d51138cd9ce894e72671d95f8a; >= e6720779ae612a14ac4ba7fe4fd5b27d900d932c, < 816fb1590a4c8cf8d05cd076057616be02e276f0
Linux	Linux	6.13

References

Timeline

Published: Oct 23, 2026
Last Modified: Oct 24, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-99011?

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata() sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a strong reference under hdev->lock: hci_dev_lock(hdev); hcon = hci_conn_hash_lookup_handle(hdev, handle); ... conn = sco_conn_hold_unless_zero(hcon->sco_data); hci_dev_unlock(hdev); but the pointer is cleared from the other side without that lock. When the last sco_conn reference is dropped, sco_conn_free() ran conn->hcon->sco_data = NULL; with no hdev->lock held, so the RX path could read hcon->sco_data and call kref_get_unless_zero() on an sco_conn that was concurrently freed: BUG: KASAN: slab-use-after-free in sco_conn_hold_unless_zero+0xbe/0x160 Write of size 4 by task kworker/u17:0 Workqueue: hci0 hci_rx_work Call Trace: sco_conn_hold_unless_zero+0xbe/0x160 sco_recv_scodata+0x13f/0x490 hci_rx_work+0x3af/0x730 kref_get_unless_zero() only guards against a zero refcount, not against the backing memory already being freed. Give hcon->sco_data an actual reference on the sco_conn it points to, so the object cannot be freed while the pointer is still installed, and only clear and drop it from sco_conn_del(), which runs under hdev->lock (its callers, sco_connect_cfm() and sco_disconn_cfm(), hold it). The reader in sco_recv_scodata() also takes hdev->lock, so the store and the read are now serialised: the RX path either observes NULL or a reference that is guaranteed to stay valid until it drops its own. sco_conn_add() no longer hands its kref_init() reference to the caller as the connection's only reference; that initial reference is the one owned by hcon->sco_data, and callers get their own via sco_conn_hold(). Because the sco_conn can now outlive the socket (the association keeps it alive until the link goes down), the hci_conn can no longer be dropped from sco_conn_free() without regressing socket close: closing a connected SCO socket must still tear the link down. Move hci_conn ownership to the socket instead: __sco_chan_add() takes an hci_conn reference and it is released from sco_chan_del() and sco_sock_destruct(), exactly once. The sco_conn no longer owns an hci_conn reference, so sco_conn_add() stops consuming one and sco_connect() drops the hci_connect_sco() reference on every path; sco_connect_cfm() no longer needs its hci_conn_hold() dance.

How severe is CVE-2026-99011?

CVE-2026-99011 has a CVSS score of 7.1/10 (HIGH severity).

How do I fix CVE-2026-99011?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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