CVE-2026-52921

What the bug is

The following hash set variants: hash:ip,mark hash:ip,port hash:ip,port,ip hash:ip,port,net iterate IPv4 ranges with a 32-bit iterator. The iterator must stop once the last address in the requested range has been processed. Advancing it once more can move the traversal state past the end of the request, so a later retry may continue from an unintended position. Handle the iterator increment explicitly at the end of the loop and stop once the upper bound has been processed. This keeps the existing retry behaviour intact for valid ranges while preventing traversal from continuing past the original boundary.

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/netfilter/ipset/ip_set_hash_ipmark.c
net/netfilter/ipset/ip_set_hash_ipport.c
net/netfilter/ipset/ip_set_hash_ipportip.c
net/netfilter/ipset/ip_set_hash_ipportnet.c

What this is

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

Kernel module

ip_set_hash_ipmark

Check it on the machine

grep -wE 'CONFIG_IP_SET|CONFIG_IP_SET_HASH_IPMARK|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 ip_set_hash_ipmark

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_IP_SET, CONFIG_IP_SET_HASH_IPMARK, 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

2026-06-24 (4 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.11%, higher than 1.4% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

net/netfilter

Upstream fixes

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

Introduced	Fixed in	Commit
4.14	5.10.258	be75218fadea
4.14	5.15.209	383418c20e69
4.14	6.1.175	0d7b33ace701
4.14	6.6.142	c281e018af98
4.14	6.12.92	02f75f041a93
4.14	6.18.34	952e988163c2
4.14	7.0.11	0b530efb2cc9
4.14	7.1	0d3a282ab5f1

Debian advisories