CVE-2026-90254 Bluetooth: hci_sync: free the advertising instance on the failure and cancel paths
A memory leak in the Linux kernel Bluetooth subsystem allows attackers to cause denial of service by triggering specific failure or cancellation paths in advertising instances.
- 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-2026-90254?
CVE-2026-90254 is a memory corruption vulnerability in Linux, published on 17 Sep 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_sync: free the advertising instance on the failure and cancel paths
adv_timeout_expire() hands a kmalloc()ed instance byte to hci_cmd_sync_queue() with a NULL destroy callback, and only adv_timeout_expire_sync() frees it. That leaks on two paths:
- the return value is not checked, and hci_cmd_sync_queue() does not take ownership when it fails (-ENETDOWN, -ENODEV, -ENOMEM);
- a cancelled entry is not released, as _hci_cmd_sync_cancel_entry() does not free entry->data when there is no destroy callback. hci_cmd_sync_clear() cancels every pending entry when the controller is unregistered.
Free the buffer from a destroy callback, and in the caller when the entry could not be queued at all.
Which versions are affected by CVE-2026-90254?
How do I fix CVE-2026-90254?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-90254 being exploited?
There is no known exploitation of CVE-2026-90254 in the wild and no public exploit code.
Sources
Also known as AZL-102884, BELL-CVE-2026-90254, DEBIAN-CVE-2026-90254, GHSA-cq3p-99wv-3cqf, UBUNTU-CVE-2026-90254.