CVE-2026-53219

What the bug is

The native and compat get-entries paths copy the fixed rule entry header from the kernelized rule blob to userspace before overwriting the entry's counter fields with a sanitized counter snapshot. On SMP kernels, entry->counters.pcnt contains the percpu allocation address used by x_tables rule counters. A caller can provide a userspace buffer that faults during the initial fixed-header copy after pcnt has been copied but before the later sanitized counter copy runs. The syscall then returns -EFAULT while leaving the raw percpu pointer in userspace. Copy only the fixed entry prefix before counters from the kernelized rule blob, then copy the sanitized counter snapshot into the counter field. Apply this ordering to the IPv4, IPv6, and ARP native and compat get-entries implementations so a fault cannot expose the internal percpu counter pointer.

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/ipv4/netfilter/arp_tables.c
net/ipv4/netfilter/ip_tables.c
net/ipv6/netfilter/ip6_tables.c

What this is

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

Kernel module

arp_tables

Check it on the machine

grep -wE 'CONFIG_INET|CONFIG_IP_NF_ARPTABLES|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 arp_tables

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, trixiem
• forky, sidMnot built on amd64/rt-amd64, arm64/rt-arm64

m

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

M

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

Build switches

CONFIG_INET, CONFIG_IP_NF_ARPTABLES, 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

0.13%, higher than 2.2% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

net/ipv4

Upstream fixes

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

Introduced	Fixed in	Commit
4.2	5.10.259	b74ba3343eb4
4.2	5.15.210	0b35dc8527cc
4.2	6.1.176	b28e2fcad3db
4.2	6.6.143	a0d16941adf3
4.2	6.12.94	8d67e42ad3b1
4.2	6.18.36	08a3e218064d
4.2	7.0.13	fb0521aff1e1
4.2	7.1	f7f2fbb0e893

Debian advisories