CVE-2026-63871

What the bug is

iso_connect_bis(), iso_connect_cis(), iso_listen_bis(), and iso_conn_big_sync() call hci_get_route() using iso_pi(sk)->dst, iso_pi(sk)->src, and iso_pi(sk)->src_type without holding lock_sock(). These fields may be modified concurrently by connect() or setsockopt() on the same socket, resulting in data-races reported by KCSAN. Fix this by snapshotting the required fields under lock_sock() before calling hci_get_route(). BUG: KCSAN: data-race in memcmp+0x45/0xb0 race at unknown origin, with read to 0xffff8880122135cf of 1 bytes by task 333 on cpu 1: memcmp+0x45/0xb0 hci_get_route+0x27e/0x490 iso_connect_cis+0x4c/0xa10 iso_sock_connect+0x60e/0xb30 __sys_connect_file+0xbd/0xe0 __sys_connect+0xe0/0x110 __x64_sys_connect+0x40/0x50 x64_sys_call+0xcad/0x1c60 do_syscall_64+0x133/0x590 entry_SYSCALL_64_after_hwframe+0x77/0x7f

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/iso.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 -wE 'CONFIG_BT|CONFIG_BT_LE' /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

M

a module where it is built at all; some flavours do not build it

Build switches

CONFIG_BT, CONFIG_BT_LE

Reads as

all on means the file is compiled; any one off means it is not.

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

no vector published, unrated

Attack vector

not published

EPSS

0.17%, higher than 5.4% 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
6.2	6.12.94	9798f7d41d85
6.2	6.18.36	ab84fd7779a2
6.2	7.0.13	859bb1f4cb61
6.2	7.1	9ca7053d6215
6.1.9	0	0