CVE-2026-64206

What the bug is

l2cap_conn_del() takes conn->lock and then calls cancel_work_sync() for pending_rx_work. process_pending_rx() takes the same mutex, so teardown can deadlock against the worker it is flushing. This issue was found by our static analysis tool and then manually reviewed against the current tree. The grounded PoC kept the l2cap_conn_ready() -> queue_work(..., &conn->pending_rx_work) submit path, the l2cap_conn_del() -> cancel_work_sync(&conn->pending_rx_work) teardown path, and the process_pending_rx() -> mutex_lock(&conn->lock) worker edge. Lockdep WARNING: possible circular locking dependency detected process_pending_rx+0x21/0x2a [vuln_msv] l2cap_conn_del.constprop.0+0x3f/0x4e [vuln_msv] *** DEADLOCK *** Cancel pending_rx_work before taking conn->lock, matching the existing lock-before-drain ordering used for the two delayed works in the same teardown path. The pending_rx queue is still purged after the work has been cancelled and conn->lock has been acquired.

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/l2cap_core.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 bluetooth

Prints 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
• bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64

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

2026-07-20 (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

0.26%, higher than 16.4% 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
3.16	5.10.261	fc0c3b9cf27c
3.16	5.15.212	9901f847a762
3.16	6.1.178	4a0bb0fd63fe
3.16	6.6.145	8daaf7f73fe9
3.16	6.12.97	8de7b386ffad
3.16	6.18.39	d5616beb3355
3.16	7.1.4	e96fbac8d3a7
3.16	7.2	2641a9e0a1dd
3.15.5	0	0

Debian advisories