CVE-2026-72051 net: ip6_tunnel: require CAP_NET_ADMIN in the device netns for changelink
A missing authorization check in the Linux kernel allows privileged users to modify IPv6 tunnels in different network namespaces, potentially leading to privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72051?
CVE-2026-72051 is a high-severity missing authorization vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: ip6_tunnel: require CAP_NET_ADMIN in the device netns for changelink
ip6_tnl_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 ip6_tnl_changelink() on rtnl_dev_link_net_capable() at its top, before any attribute is parsed.
Weakness: CWE-862
Which versions are affected by CVE-2026-72051?
How do I fix CVE-2026-72051?
Apply the vendor's patch.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-72051 being exploited?
There is no known exploitation of CVE-2026-72051 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72051, DEBIAN-CVE-2026-72051, GHSA-q3jr-w6wf-464w, UBUNTU-CVE-2026-72051.