CVE-2026-43021 Bluetooth: hci_sync: fix leaks when hci_cmd_sync_queue_once fails
A memory leak in the Linux kernel Bluetooth subsystem can lead to resource exhaustion and denial of service when command queuing fails.
- 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-2026-43021?
CVE-2026-43021 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 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_sync: fix leaks when hci_cmd_sync_queue_once fails
When hci_cmd_sync_queue_once() returns with error, the destroy callback will not be called.
Fix leaking references / memory on these failures.
Weakness: CWE-401
Which versions are affected by CVE-2026-43021?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43021?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-43021 being exploited?
There is no known exploitation of CVE-2026-43021 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2026-43021, GHSA-7vq8-6v9j-p4jg, ROOT-OS-DEBIAN-11-CVE-2026-43021, ROOT-OS-DEBIAN-12-CVE-2026-43021, ROOT-OS-UBUNTU-2204-CVE-2026-43021, ROOT-OS-UBUNTU-2404-CVE-2026-43021 and 1 more.