CVE-2026-64539

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> Bluetooth: eir: Fix stack OOB write when prepending the Flags AD<br /> <br /> eir_create_adv_data() builds the advertising data into a fixed-size<br /> buffer ("size", 31 for the legacy path). It may prepend a 3-byte "Flags"<br /> AD structure (LE_AD_NO_BREDR on an LE-only controller) and then copies<br /> the per-instance data without checking that it still fits:<br /> <br /> memcpy(ptr, adv-&gt;adv_data, adv-&gt;adv_data_len);<br /> <br /> tlv_data_max_len() only reserves those 3 bytes when the user-supplied<br /> flags carry a managed-flags bit, so an instance added with flags == 0 is<br /> accepted with adv_data_len up to the full buffer. At advertise time the<br /> flags are still prepended, and the memcpy() writes 3 + adv_data_len<br /> bytes into the size-byte buffer:<br /> <br /> BUG: KASAN: stack-out-of-bounds in eir_create_adv_data (net/bluetooth/eir.c:301)<br /> Write of size 31 at addr ffff88800a547bdc by task kworker/u9:0/65<br /> Workqueue: hci0 hci_cmd_sync_work<br /> __asan_memcpy (mm/kasan/shadow.c:106)<br /> eir_create_adv_data (net/bluetooth/eir.c:301)<br /> hci_update_adv_data_sync (net/bluetooth/hci_sync.c:1310)<br /> hci_schedule_adv_instance_sync (net/bluetooth/hci_sync.c:1817)<br /> hci_cmd_sync_work (net/bluetooth/hci_sync.c:332)<br /> This frame has 1 object:<br /> [32, 64) &amp;#39;cp&amp;#39;<br /> <br /> The "Flags" structure is added by the kernel, not requested by<br /> userspace, so only prepend it when it fits together with the instance<br /> advertising data; when there is no room for both, drop the flags rather<br /> than the user-provided data.<br /> <br /> Reachable by a local user with CAP_NET_ADMIN owning an LE-only<br /> controller on the legacy advertising path.