CVE-2026-64539
Received
Received - Intake
Bluetooth Stack OOB Write in Linux Kernel
Vulnerability report for CVE-2026-64539, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-07-27
Last updated on: 2026-07-27
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: eir: Fix stack OOB write when prepending the Flags AD
eir_create_adv_data() builds the advertising data into a fixed-size
buffer ("size", 31 for the legacy path). It may prepend a 3-byte "Flags"
AD structure (LE_AD_NO_BREDR on an LE-only controller) and then copies
the per-instance data without checking that it still fits:
memcpy(ptr, adv->adv_data, adv->adv_data_len);
tlv_data_max_len() only reserves those 3 bytes when the user-supplied
flags carry a managed-flags bit, so an instance added with flags == 0 is
accepted with adv_data_len up to the full buffer. At advertise time the
flags are still prepended, and the memcpy() writes 3 + adv_data_len
bytes into the size-byte buffer:
BUG: KASAN: stack-out-of-bounds in eir_create_adv_data (net/bluetooth/eir.c:301)
Write of size 31 at addr ffff88800a547bdc by task kworker/u9:0/65
Workqueue: hci0 hci_cmd_sync_work
__asan_memcpy (mm/kasan/shadow.c:106)
eir_create_adv_data (net/bluetooth/eir.c:301)
hci_update_adv_data_sync (net/bluetooth/hci_sync.c:1310)
hci_schedule_adv_instance_sync (net/bluetooth/hci_sync.c:1817)
hci_cmd_sync_work (net/bluetooth/hci_sync.c:332)
This frame has 1 object:
[32, 64) 'cp'
The "Flags" structure is added by the kernel, not requested by
userspace, so only prepend it when it fits together with the instance
advertising data; when there is no room for both, drop the flags rather
than the user-provided data.
Reachable by a local user with CAP_NET_ADMIN owning an LE-only
controller on the legacy advertising path.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
