CVE-2026-53220

What the bug is

ebt_redirect_tg() dereferences br_port_get_rcu() return without a NULL check, causing a kernel panic when the bridge port has been removed between the original hook invocation and an NFQUEUE reinject. A mere NULL check isn't sufficient, however. As sashiko review points out userspace can not only remove the port from the bridge, it could also place the device in a different virtual device, e.g. macvlan. If this happens, we must drop the packet, there is no way for us to reinject it into the bridge path. Switch to _upper API, we don't need the bridge port structure. Also, this fix keeps another bug intact: Both nfnetlink_log and nfnetlink_queue use CONFIG_BRIDGE_NETFILTER too aggressive, which prevents certain logging features when queueing in bridge family: NETFILTER_FAMILY_BRIDGE can be enabled while the old CONFIG_BRIDGE_NETFILTER cruft is off. Fixes tag is a common ancestor, this was always broken.

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/bridge/netfilter/ebt_dnat.c
net/bridge/netfilter/ebt_redirect.c
net/netfilter/nfnetlink_log.c
net/netfilter/nfnetlink_queue.c

What this is

NETFILTERMAINTAINERS section matched on net/*/netfilter/ · netfilter-devel@vger.kernel.org · Maintained

Kernel module

ebt_dnat

Check it on the machine

grep -wE 'CONFIG_BRIDGE|CONFIG_BRIDGE_EBT_DNAT|CONFIG_NETFILTER' /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 ebt_dnat

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 as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.

• bookworm, trixie, forky, sidm

m

a loadable module on every flavour - check lsmod, can be blacklisted

Build switches

CONFIG_BRIDGE, CONFIG_BRIDGE_EBT_DNAT, CONFIG_NETFILTER

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

2026-06-25 (4 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.12%, higher than 1.8% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

net/bridge

Upstream fixes

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

Introduced	Fixed in	Commit
2.6.36	6.12.94	43330a1e8aac
2.6.36	6.18.36	4beffcd726e2
2.6.36	7.0.13	d4b1301fd3c9
2.6.36	7.1	ccb9fd4b8753