CVE-2026-46111 Bluetooth: hci_conn: fix potential UAF in create_big_sync
A use-after-free in the Linux kernel Bluetooth subsystem allows attackers to execute arbitrary code or escalate privileges via crafted Bluetooth connections.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-46111?
CVE-2026-46111 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 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: hci_conn: fix potential UAF in create_big_sync
Add hci_conn_valid() check in create_big_sync() to detect stale connections before proceeding with BIG creation. Handle the resulting -ECANCELED in create_big_complete() and re-validate the connection under hci_dev_lock() before dereferencing, matching the pattern used by create_le_conn_complete() and create_pa_complete().
Keep the hci_conn object alive across the async boundary by taking a reference via hci_conn_get() when queueing create_big_sync(), and dropping it in the completion callback. The refcount and the lock are complementary: the refcount keeps the object allocated, while hci_dev_lock() serializes hci_conn_hash_del()'s list_del_rcu() on hdev->conn_hash, as required by hci_conn_del().
hci_conn_put() is called outside hci_dev_unlock() so the final put (which resolves to kfree() via bt_link_release) does not run under hdev->lock, though the release path would be safe either way.
Without this, create_big_complete() would unconditionally dereference the conn pointer on error, causing a use-after-free via hci_connect_cfm() and hci_conn_del().
Weakness: CWE-416
Which versions are affected by CVE-2026-46111?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46111?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-46111 being exploited?
There is no known exploitation of CVE-2026-46111 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-89007, BELL-CVE-2026-46111, DEBIAN-CVE-2026-46111, GHSA-926m-qfg2-2w89, ROOT-OS-DEBIAN-12-CVE-2026-46111, ROOT-OS-UBUNTU-2404-CVE-2026-46111 and 1 more.