CVE-2025-68304

Bluetooth: hci_core: lookup hci_conn on RX path on protocol side

Published Dec 16, 2025 CVSS 3.1 · 8.8 High EPSS < 1% KEV · Not listed
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)

Analysis

No analysis available yet

Remediation

No remediation available yet

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8094-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8094-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8094-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-8094-4 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8094-5 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-8152-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8781-1 Linux kernel (NVIDIA Tegra) vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Type Values Removed Values Added
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)
Title Bluetooth: hci_core: lookup hci_conn on RX path on protocol side
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

No weakness.

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 15, 2026, 10:02 PM
Reserved
Dec 16, 2025, 2:48 PM
Status
Deferred
Published
Dec 16, 2025, 4:16 PM
Modified
Oct 15, 2026, 10:19 PM
Severity
Important
Public date
Dec 16, 2025, 12:00 AM