CVE-2026-98370

What the bug is

xfrm_state_netlink() builds the ALLOCSPI response with dump_one_state(), which already calls alloc_compat() with the response skb and header. xfrm_alloc_userspi() then calls alloc_compat() again, but passes the original request skb and its header. For a compat request, the translator therefore interprets the 228-byte compat xfrm_userspi_info as the 232-byte native layout and reads four bytes past the declared payload. It also publishes the translated child through the request's frag_list. A multicast clone of the request shares skb_shared_info and can observe that child. xfrm_user_rcv_msg() frees it after the request handler returns, racing a compat receiver which may still be copying from it and resulting in a use-after-free. Remove the redundant conversion. The response keeps its correct compat translation from dump_one_state(), and no child is attached to the inbound request.

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/xfrm/xfrm_user.c

What this is

NETWORKING [IPSEC]MAINTAINERS section matched on net/xfrm/ · netdev@vger.kernel.org · Maintained

Kernel module

xfrm_user

Check it on the machine

grep -wE 'CONFIG_XFRM|CONFIG_XFRM_USER' /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 xfrm_user

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_XFRM, CONFIG_XFRM_USER

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

2026-10-06 (13 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.17%, higher than 6.1% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

net/xfrm

Upstream fixes

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

Introduced	Fixed in	Commit
5.10	5.10.271	494f2bee9d8d
5.10	5.15.222	17893987e529
5.10	6.1.189	42971ea17c7a
5.10	6.6.158	2b63341e2ebc
5.10	6.12.112	bb63ab52a182
5.10	6.18.54	248433942155
5.10	7.2.8	e70f639aee2f
5.10	7.3	d1ebd9081879

Debian advisories