# CVE-2026-31500

> Vulnerability · severity: **HIGH** (CVSS 7.8).

## Description

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

## Key facts

- **CVE ID:** CVE-2026-31500
- **Published:** 2026-04-22
- **CVSS severity:** HIGH
- **CVSS base score:** 7.8
- **CWE codes:** CWE-416

## Affected products

- `linux:linux_kernel`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31500

## Citation

> AI Analytics. CVE-2026-31500. Retrieved 2026-08-11 from https://api.ai-analytics.org/cve/CVE-2026-31500. Derived from NIST NVD. Licensed CC0.

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