CVE-2026-98625

What the bug is

flow_offload_work_del() sets NF_FLOW_HW_DEAD before the work handler clears NF_FLOW_HW_PENDING. Once a flow is both HW_DYING and HW_DEAD, a concurrent garbage collection pass can remove it and schedule it for RCU freeing. The offload worker holds neither an RCU read lock nor a reference to the flow. If it is preempted after publishing HW_DEAD, the RCU callback can free the flow before the worker resumes and clears HW_PENDING, resulting in a use-after-free. Move HW_DEAD publication to the common worker epilogue after the pending bit is cleared, making it the final flow access by destroy work. Order all preceding flow accesses before publishing the bit that allows garbage collection to free the object.

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/nf_flow_table_offload.c

What this is

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

Kernel module

nf_flow_table

Check it on the machine

grep -wE 'CONFIG_NETFILTER|CONFIG_NF_FLOW_TABLE' /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 nf_flow_table

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_NETFILTER, CONFIG_NF_FLOW_TABLE

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

2026-10-18 (today)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

not scored

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
5.7	5.10.271	f92e8f39726b
5.7	5.15.222	00e452a7ca9f
5.7	6.1.189	56f39c7d139b
5.7	6.6.158	e20701843032
5.7	6.12.112	b4f0f05dfbe8
5.7	6.18.55	b0ef9450e93f
5.7	7.2.9	f26652e99f51
5.7	7.3	d644b23afe1e