CVE-2026-68142 geneve: require CAP_NET_ADMIN in the device netns for changelink
Attackers with limited network namespace privileges can modify Geneve tunnel configurations in other namespaces, bypassing authorization checks.
- 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-2026-68142?
CVE-2026-68142 is a high-severity missing authorization vulnerability in Linux, published on 10 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:
geneve: require CAP_NET_ADMIN in the device netns for changelink
A tunnel changelink() operates on at most two netns, dev_net(dev) and the sticky underlay netns geneve->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 geneve->net can rewrite a geneve device whose underlay lives in geneve->net.
geneve_changelink() applies the new configuration against geneve->net: geneve_link_config() and the geneve_quiesce()/geneve_unquiesce() pair reopen the underlay sockets in that netns (geneve_sock_add() uses geneve->net), so the same reasoning as the tunnel changelink series applies here.
Gate geneve_changelink() with rtnl_dev_link_net_capable(), at the top of the op before any attribute is parsed, matching ipgre_changelink() and the rest of the "require CAP_NET_ADMIN in the device netns for changelink" series.
Found by 0sec automated security-research tooling (https://0sec.ai).
Weakness: CWE-862
Which versions are affected by CVE-2026-68142?
How do I fix CVE-2026-68142?
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-2026-68142 being exploited?
There is no known exploitation of CVE-2026-68142 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68142, DEBIAN-CVE-2026-68142, GHSA-2rrg-cg9g-pgvw, UBUNTU-CVE-2026-68142.