CVE-2026-72055: net: ip6_vti: require CAP_NET_ADMIN in the device netns for changelink

CVE-2026-72055: net: ip6_vti: require CAP_NET_ADMIN in the device netns for changelink

[Greg Kroah-Hartman]

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

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

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

net: ip6_vti: require CAP_NET_ADMIN in the device netns for changelink

vti6_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 vti6_changelink() on rtnl_dev_link_net_capable() at its top,
before any attribute is parsed.

The Linux kernel CVE team has assigned CVE-2026-72055 to this issue.


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

	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 5.10.261 with commit f5254e7766b4ac02b66b2ccef896cd278503cb11
	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 5.15.212 with commit ef897249dc957089e6f7f11ceea699e093ad51bd
	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 6.1.178 with commit f6e8b52a2cb3bbd72ddc2d44e474b907b9dcf5ba
	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 6.6.145 with commit c64b9ae7eb97e81d54b792910a3aeafd92566c79
	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 6.12.97 with commit b2b61c540571b3cc2f461e2a579ba2cc8c2a52cf
	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 6.18.40 with commit 0b2f9c908f930ec4be17d389723f9a202d6a883c
	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 7.1.5 with commit f97e93ebf2f9b8ef3b87f7a9371255e84d151587
	Issue introduced in 3.15 with commit 61220ab349485d911083d0b7990ccd3db6c63297 and fixed in 7.2-rc1 with commit e2ac3b242c37dff323a964962e43854f4b1a2b79

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-2026-72055
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/ipv6/ip6_vti.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/f5254e7766b4ac02b66b2ccef896cd278503cb11
	https://git.kernel.org/stable/c/ef897249dc957089e6f7f11ceea699e093ad51bd
	https://git.kernel.org/stable/c/f6e8b52a2cb3bbd72ddc2d44e474b907b9dcf5ba
	https://git.kernel.org/stable/c/c64b9ae7eb97e81d54b792910a3aeafd92566c79
	https://git.kernel.org/stable/c/b2b61c540571b3cc2f461e2a579ba2cc8c2a52cf
	https://git.kernel.org/stable/c/0b2f9c908f930ec4be17d389723f9a202d6a883c
	https://git.kernel.org/stable/c/f97e93ebf2f9b8ef3b87f7a9371255e84d151587
	https://git.kernel.org/stable/c/e2ac3b242c37dff323a964962e43854f4b1a2b79