CVE-2026-72116

What the bug is

RX: an RX_SETUP update(!) for an existing op skipped can_rx_register() unconditionally, even when a concurrent NETDEV_UNREGISTER had already torn down its registration (op->rx_reg_dev == NULL). This silently did not re-enable frame delivery for that updated filter. bcm_rx_setup() now re-registers in that case, while leaving rx_ops with ifindex = 0 (all CAN devices) which never carry a tracked rx_reg_dev registered as-is. TX: bcm_notify() only handled bo->rx_ops on NETDEV_UNREGISTER, leaving tx_ops with an active cyclic transmission re-arming its hrtimer indefinitely to execute bcm_tx_timeout_handler(). Cancelling the hrtimer prevents the runaway timer and any injection into a later reused ifindex, since nothing else calls bcm_can_tx() for the op until an explicit TX_SETUP update re-arms it. Unlike bcm_rx_unreg(), which clears the tracked rx_reg_dev for rx_ops, the ifindex is intentionally left unchanged for tx_ops. bcm_tx_setup() always rejects ifindex 0, so clearing it would strand the op: neither a later TX_SETUP (bcm_find_op()) nor TX_DELETE (bcm_delete_tx_op()) could ever find it again, since both require an exact ifindex match.

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/can/bcm.c

What this is

CAN NETWORK LAYERMAINTAINERS section matched on net/can/ · linux-can@vger.kernel.org · Maintained

Kernel module

can_bcm

Check it on the machine

grep -wE 'CONFIG_CAN|CONFIG_CAN_BCM' /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 can_bcm

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.

• bookworm, trixie, forky, sid, 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 switches

CONFIG_CAN, CONFIG_CAN_BCM

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

2026-08-15 (2 months ago)source

CVSS

7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsource recompute it

Attack vector

local (AV:L)source

EPSS

0.19%, higher than 7.6% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

net/can

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
2.6.25	5.10.265	d30a36066ed3
2.6.25	5.15.216	ca829677ffa2
2.6.25	6.1.183	9517d8fb0b19
2.6.25	6.6.148	60d8a7942f4e
2.6.25	6.12.101	f749e4564952
2.6.25	6.18.42	6be3e1fedf03
2.6.25	7.1.5	b31d0933509c
2.6.25	7.2	3b762c0d9503

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