# CVE-2025-68304: Bluetooth: hci_core: lookup hci_conn on RX path on protocol side

CVE-2025-68304 is fixed in linux on 1 platform by DEBIAN-CVE-2025-68304 (version 6.17.11-1), released December 16, 2025. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-68304
- Priority: High
- CVSS: 8.8 (Important)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 16, 2025
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-68304

## Description

In the Linux kernel, the following vulnerability has been resolved:  Bluetooth: hci_core: lookup hci_conn on RX path on protocol side  The hdev lock/lookup/unlock/use pattern in the packet RX path doesn't ensure hci_conn* is not concurrently modified/deleted. This locking appears to be leftover from before conn_hash started using RCU commit bf4c63252490b ("Bluetooth: convert conn hash to RCU") and not clear if it had purpose since then.  Currently, there are code paths that delete hci_conn* from elsewhere than the ordered hdev->workqueue where the RX work runs in. E.g. commit 5af1f84ed13a ("Bluetooth: hci_sync: Fix UAF on hci_abort_conn_sync") introduced some of these, and there probably were a few others before it.  It's better to do the locking so that even if these run concurrently no UAF is possible.  Move the lookup of hci_conn and associated socket-specific conn to protocol recv handlers, and do them within a single critical section to cover hci_conn* usage and lookup.  syzkaller has reported a crash that appears to be this issue:      [Task hdev->workqueue]          [Task 2]                                     hci_disconnect_all_sync     l2cap_recv_acldata(hcon)                                       hci_conn_get(hcon)                                       hci_abort_conn_sync(hcon)                                         hci_dev_lock       hci_dev_lock                                         hci_conn_del(hcon)       v-------------------------------- hci_dev_unlock                                       hci_conn_put(hcon)       conn = hcon->l2cap_data (UAF)

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.17.11-1 | [DEBIAN-CVE-2025-68304](https://patchblox.com/security/data/fix/linux/debian-cve-2025-68304.md) | Dec 16, 2025 |

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