CVE-2026-80683 is a vulnerability in Linux Kernel
Published on August 28, 2026
Bluetooth: SCO: give the socket its own sco_conn reference
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: SCO: give the socket its own sco_conn reference
sco_conn_del() drops a reference it does not own. It takes one transient
reference via sco_conn_hold_unless_zero() and releases it with the
sco_conn_put() that follows sco_sock_hold(); the additional put in the
!sk branch releases a second one:
conn = sco_conn_hold_unless_zero(conn);
...
sk = sco_sock_hold(conn);
sco_conn_unlock(conn);
sco_conn_put(conn);
if (!sk) {
sco_conn_put(conn);
return;
}
When close() races the controller's Disconnection Complete, sco_chan_del()
clears conn->sk and drops the socket's reference while sco_conn_del() is
running. sco_conn_del() then sees sk == NULL, its own put drops the count
to zero and frees the conn, and the second put writes to the freed kref:
BUG: KASAN: slab-use-after-free in sco_conn_put.part.0+0x1a/0x190
Write of size 4 at addr ffff8881099dec74 by task kworker/u17:3/413
Workqueue: hci1 hci_rx_work
Call Trace:
sco_conn_put.part.0+0x1a/0x190
hci_disconn_complete_evt+0x1ee/0x3e0
hci_event_packet+0x54a/0x650
hci_rx_work+0x321/0x3d0
Allocated by task 413:
sco_conn_add+0x72/0x1a0
sco_connect_cfm+0x88/0x670
Freed by task 413:
sco_conn_del.isra.0+0x3f/0xf0
hci_disconn_complete_evt+0x1ee/0x3e0
refcount_t: underflow; use-after-free.
The root cause is that the socket stores the connection without holding a
reference of its own. __sco_chan_add() does:
sco_pi(sk)->conn = conn;
so the socket borrows whatever reference its caller happened to hold, and
the callers paper over that with ad-hoc holds and puts. Give the socket a
counted reference instead: __sco_chan_add() takes one and it is released
together with the channel (sco_chan_del()) and in sco_sock_destruct().
With the socket holding its own reference, sco_conn_del() no longer needs
the extra put and the redundant hold in sco_conn_ready() goes away.
Making the socket own its reference means the connection is now actually
freed on the error paths of sco_connect() where it used to leak, which in
turn runs sco_conn_free() and its hci_conn_drop(conn->hcon). To keep the
hci_conn accounting balanced, make that ownership explicit as well:
sco_conn_add() consumes one hci_conn reference and the sco_conn owns it for
its lifetime. sco_connect() hands over the reference returned by
hci_connect_sco() and no longer drops it on the error paths;
sco_connect_cfm(), which is not given a reference, takes one with
hci_conn_hold() before handing it to sco_conn_add() (and drops it again if
the allocation fails); and the explicit hci_conn_hold() in sco_conn_ready()
is removed. Every reference then has a single, clear owner.
Products Associated with CVE-2026-80683
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Affected Versions
Linux:- Version e6720779ae612a14ac4ba7fe4fd5b27d900d932c and below a33bc07b4730b6cd5681ac77d18ae0de3e739690 is affected.
- Version e6720779ae612a14ac4ba7fe4fd5b27d900d932c and below 8fe627192fa5da7157f9a48608f13c04b6373e43 is affected.
- Version e6720779ae612a14ac4ba7fe4fd5b27d900d932c and below abd93c85c8667add738ee82aeab95dd9fc8265a2 is affected.
- Version 6.13 is affected.
- Before 6.13 is unaffected.
- Version 6.18.44, <= 6.18.* is unaffected.
- Version 7.1.8, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.