CVE-2026-53209 Bluetooth: hci_sync: reject oversized Broadcast Announcement prepend
A buffer overflow in the Linux kernel Bluetooth subsystem allows attackers to cause denial of service or potentially execute code via oversized broadcast announcements.
- 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-2026-53209?
CVE-2026-53209 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Jun 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: reject oversized Broadcast Announcement prepend
Existing advertising instances can already hold the maximum extended advertising payload. When hci_adv_bcast_annoucement() prepends the Broadcast Announcement service data to that payload, the combined data may no longer fit in the temporary buffer used to rebuild the advertising data.
Reject that case before copying the existing payload and report the failure through the device log. This keeps the existing advertising data intact and avoids overrunning the temporary buffer.
Which versions are affected by CVE-2026-53209?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53209?
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-2026-53209 being exploited?
There is no known exploitation of CVE-2026-53209 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90323, BELL-CVE-2026-53209, DEBIAN-CVE-2026-53209, GHSA-jfwg-qvfj-22x4, ROOT-OS-DEBIAN-12-CVE-2026-53209, ROOT-OS-UBUNTU-2404-CVE-2026-53209 and 1 more.