CVE-2026-72053: net: ipip: require CAP_NET_ADMIN in the device netns for changelink

From: Greg Kroah-Hartman <[email protected]>

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

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

net: ipip: require CAP_NET_ADMIN in the device netns for changelink

ipip_changelink() operates on at most two netns, dev_net(dev) and the
tunnel link netns t->net. They differ once the device is created in or
moved to a netns other than the one the request runs in. The rtnl
changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a
caller privileged there but not in t->net can rewrite a tunnel that
lives in t->net.

Gate ipip_changelink() on rtnl_dev_link_net_capable() at its top,
before any attribute is parsed.

The Linux kernel CVE team has assigned CVE-2026-72053 to this issue.


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

	Issue introduced in 3.12 with commit 6c742e714d8c282fd8f8b22d3e20b5141738c1ee and fixed in 6.1.178 with commit 91571643e554ae89a91942380d5f5361fb7060a2
	Issue introduced in 3.12 with commit 6c742e714d8c282fd8f8b22d3e20b5141738c1ee and fixed in 6.6.145 with commit 983cc4aa7e6f633b34c3ee743771252d7afa9a90
	Issue introduced in 3.12 with commit 6c742e714d8c282fd8f8b22d3e20b5141738c1ee and fixed in 6.12.97 with commit 26544021d5c49cc6ae8a968ccb5033e6363854a4
	Issue introduced in 3.12 with commit 6c742e714d8c282fd8f8b22d3e20b5141738c1ee and fixed in 6.18.40 with commit 68cadc3698c7de88966d306d12ec9c6217da228a
	Issue introduced in 3.12 with commit 6c742e714d8c282fd8f8b22d3e20b5141738c1ee and fixed in 7.1.5 with commit d49edcc65e0a37cc9b386a94415c5d6670ca8b71
	Issue introduced in 3.12 with commit 6c742e714d8c282fd8f8b22d3e20b5141738c1ee and fixed in 7.2-rc1 with commit 8211a26324667980a463c069469a818e71207e02

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-2026-72053
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/ipv4/ipip.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/91571643e554ae89a91942380d5f5361fb7060a2
	https://git.kernel.org/stable/c/983cc4aa7e6f633b34c3ee743771252d7afa9a90
	https://git.kernel.org/stable/c/26544021d5c49cc6ae8a968ccb5033e6363854a4
	https://git.kernel.org/stable/c/68cadc3698c7de88966d306d12ec9c6217da228a
	https://git.kernel.org/stable/c/d49edcc65e0a37cc9b386a94415c5d6670ca8b71
	https://git.kernel.org/stable/c/8211a26324667980a463c069469a818e71207e02