CVE-2026-74533 Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero
A race condition in the Linux kernel Bluetooth ISO subsystem allows use-after-free, potentially enabling code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74533?
CVE-2026-74533 is a high-severity vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero
hci_conn::iso_data is accessed and modified without lock or RCU. This leads to a race
[Task hdev->workqueue] [Task 2] iso_recv iso_conn_put(conn) conn = LOAD hcon->iso_data iso_conn_free(conn) iso_conn_hold_unless_zero(conn) hcon->iso_data = NULL kfree(conn) kref_get_unless_zero(&conn->ref) /* UAF */
and also to races in iso_conn_add() vs. iso_conn_free().
Fix by adding spinlock hci_conn::proto_lock and using it to guard hci_conn::iso_data.
Which versions are affected by CVE-2026-74533?
How do I fix CVE-2026-74533?
Apply the vendor's patch.
Is CVE-2026-74533 being exploited?
There is no known exploitation of CVE-2026-74533 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74533, DEBIAN-CVE-2026-74533, GHSA-xf88-xmxw-hhch, UBUNTU-CVE-2026-74533.