Linux Kernel Bluetooth stack Use-After-Free Rated 7.8 CVSS

Status: UPDATED  |  Advisory ID: CVE-2026-31500

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: btintel: serialize btintel_hw_error() with hci_req_sync_lock

btintel_hw_error() issues two __hci_cmd_sync() calls (HCI_OP_RESET

and Intel exception-info retrieval) without holding

hci_req_sync_lock(). This lets it race against

hci_dev_do_close() -> btintel_shutdown_combined(), which also runs

__hci_cmd_sync() under the same lock. When both paths manipulate

hdev->req_status/req_rsp concurrently, the close path may free the

response skb first, and the still-running hw_error path hits a

slab-use-after-free in kfree_skb().

Wrap the whole recovery sequence in hci_req_sync_lock/unlock so it

is serialized with every other synchronous HCI command issuer.

Below is the data race report and the kasan report:

BUG: data-race in __hci_cmd_sync_sk / btintel_shutdown_combined

read of hdev->req_rsp at net/bluetooth/hci_sync.c:199

by task kworker/u17:1/83:

__hci_cmd_sync_sk+0x12f2/0x1c30 net/bluetooth/hci_sync.c:200

__hci_cmd_sync+0x55/0x80 net/bluetooth/hci_sync.c:223

btintel_hw_error+0x114/0x670 drivers/bluetooth/btintel.c:254

hci_error_reset+0x348/0xa30 net/bluetooth/hci_core.c:1030

write/free by task ioctl/22580:

btintel_shutdown_combined+0xd0/0x360

drivers/bluetooth/btintel.c:3648

hci_dev_close_sync+0x9ae/0x2c10 net/bluetooth/hci_sync.c:5246

hci_dev_do_close+0x232/0x460 net/bluetooth/hci_core.c:526

BUG: KASAN: slab-use-after-free in

sk_skb_reason_drop+0x43/0x380 net/core/skbuff.c:1202

Read of size 4 at addr ffff888144a738dc

by task kworker/u17:1/83:

__hci_cmd_sync_sk+0x12f2/0x1c30 net/bluetooth/hci_sync.c:200

__hci_cmd_sync+0x55/0x80 net/bluetooth/hci_sync.c:223

btintel_hw_error+0x186/0x670 drivers/bluetooth/btintel.c:260 (NVD)

What to Do

Monitor Linux's and Siemens's web pages for any future patch releases.

References