CVE-2026-72061: net: sit: 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: sit: require CAP_NET_ADMIN in the device netns for changelink

ipip6_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 ipip6_changelink() on rtnl_dev_link_net_capable() at its top,
before any attribute is parsed. sit was the one tunnel type not covered
by the recent series that added this check to the other changelink()
handlers.

The Linux kernel CVE team has assigned CVE-2026-72061 to this issue.


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

	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 5.10.261 with commit cb41b308e9d867725d965b291dd085028e36a480
	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 5.15.212 with commit c5a0ae895432596b2f464172da8218e2d84e2932
	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 6.1.178 with commit 7d139dec96691cde96cb40ed293e2d13d994fb4f
	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 6.6.145 with commit 388ccffbd2e7e5e4271f291085a7451865705305
	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 6.12.97 with commit c0ea1aedb37bb979e864ed7787975434bbd9db73
	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 6.18.40 with commit 3118e97dae533fb45964b87bbed1801afcff7c65
	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 7.1.5 with commit 99ae3248b33df94201915d9c32e7470cdf08cfcd
	Issue introduced in 3.11 with commit 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 and fixed in 7.2-rc1 with commit 27ccb68e7cccead5d8c611665a45d23032d468b3

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-2026-72061
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/sit.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/cb41b308e9d867725d965b291dd085028e36a480
	https://git.kernel.org/stable/c/c5a0ae895432596b2f464172da8218e2d84e2932
	https://git.kernel.org/stable/c/7d139dec96691cde96cb40ed293e2d13d994fb4f
	https://git.kernel.org/stable/c/388ccffbd2e7e5e4271f291085a7451865705305
	https://git.kernel.org/stable/c/c0ea1aedb37bb979e864ed7787975434bbd9db73
	https://git.kernel.org/stable/c/3118e97dae533fb45964b87bbed1801afcff7c65
	https://git.kernel.org/stable/c/99ae3248b33df94201915d9c32e7470cdf08cfcd
	https://git.kernel.org/stable/c/27ccb68e7cccead5d8c611665a45d23032d468b3