Look up another CVE · open CVE-2026-63974 in the interactive tracker
CVE-2026-63974
Bluetooth: hci_sync: Set HCI_CMD_DRAIN_WORKQUEUE during device close
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/bluetooth. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-63974 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Since hci_dev_close_sync() can now be called during the reset path, we should also set HCI_CMD_DRAIN_WORKQUEUE. This avoids queuing timeouts while the hdev workqueue is being drained.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/bluetooth/hci_sync.c
- What this is
- BLUETOOTH SUBSYSTEMMAINTAINERS section matched on net/bluetooth/ · linux-bluetooth@vger.kernel.org · Supported
- Kernel module
- bluetooth
Check it on the machine
grep -w CONFIG_BT /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w bluetoothPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_BT
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-07-19 (3 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.32%, higher than 23.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/bluetooth
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.0 | 6.12.93 | 9cebe4680bb9 |
| 6.0 | 6.18.35 | 47330cc875b3 |
| 6.0 | 7.0.12 | 60bceb9a4c69 |
| 6.0 | 7.1 | 525daaea459f |
| 5.18.18 | 0 | 0 |
| 5.19.2 | 0 | 0 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:AAttack vector, adjacent network
- This is a Bluetooth HCI subsystem bug where exploitation requires concurrent HCI controller events from the radio during adapter close/reset; on phones and laptops with Bluetooth enabled in public spaces, a nearby attacker can supply that traffic while the kernel tears down the adapter.
- AC:LAttack complexity, low
- The attacker controls both sides of the race by timing Bluetooth traffic against adapter reset/close or error-recovery teardown, and syzbot reliably reproduced the original workqueue-drain class of this bug.
- PR:NPrivileges required, none
- No local credentials are required on the remote path: a nearby Bluetooth attacker can drive ncmd/cmd timeout recovery that calls hci_dev_do_close() → hci_dev_close_sync(); local CAP_NET_ADMIN ioctl reset is an additional reachable path via user namespaces.
- UI:NUser interaction, none
- Exploitation does not require the victim to perform a specific action beyond having Bluetooth enabled, which is the default on most mobile and laptop deployments.
- S:UScope, unchanged
- Impact is confined to kernel Bluetooth/HCI state and does not cross a security boundary such as a VM escape or sandbox breakout.
- C:HConfidentiality impact, high
- Queueing work onto a draining workqueue corrupts kernel workqueue metadata for cmd_timer/ncmd_timer delayed-work structures, which is memory corruption that could be leveraged for information disclosure during the close/open reset cycle.
- I:HIntegrity impact, high
- The workqueue invariant violation leaves delayed-work items in inconsistent states on a persistent hdev->workqueue that is reused after reset, creating a plausible path to control-flow hijack via corrupted work callbacks.
- A:HAvailability impact, high
- Triggering this bug produces a kernel WARNING in __queue_work() (kernel panic on panic_on_warn systems) and can cause drain_workqueue() to spin with repeated reflush attempts, denying Bluetooth availability and potentially hanging the adapter teardown path.