CVE-2026-72249: netfilter: flowtable: use dst in this direction when pushing IPIP header

CVE-2026-72249: netfilter: flowtable: use dst in this direction when pushing IPIP header

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

netfilter: flowtable: use dst in this direction when pushing IPIP header

When pushing the IPIP header, the route of the other direction is used
to calculate the headroom, use the route in this direction. Accessing
the other tuple to set the IP source and destination is fine because
this tuple does not provide such information to avoid storing redundant
information. However, this tuple already provides the dst for this
direction, this went unnoticed because this bug affects headroom and
iph->frag_off only at this stage.

The Linux kernel CVE team has assigned CVE-2026-72249 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.19 with commit d30301ba4b07ac92eb38353a111833b009003170 and fixed in 7.1.5 with commit ecb78fbb03d3f86e2e93767875e273308086a424
	Issue introduced in 6.19 with commit d30301ba4b07ac92eb38353a111833b009003170 and fixed in 7.2-rc3 with commit c328b90c17fc5fa7786503695152880b2afb9326

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-72249
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/netfilter/nf_flow_table_ip.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/ecb78fbb03d3f86e2e93767875e273308086a424
	https://git.kernel.org/stable/c/c328b90c17fc5fa7786503695152880b2afb9326