CVE-2026-46120

/// Technical description

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

ip6_gre: Use cached t->net in ip6erspan_changelink().

After commit 5e72ce3e3980 ("net: ipv6: Use link netns in newlink() of

rtnl_link_ops"), ip6erspan_newlink() correctly resolves the per-netns

ip6gre hash via link_net. ip6erspan_changelink() was not converted in

that series and still uses dev_net(dev), which diverges from the

device's creation netns after IFLA_NET_NS_FD migration.

This re-inserts the tunnel into the wrong per-netns hash. The

original netns keeps a stale entry. When that netns is later

destroyed, ip6gre_exit_rtnl_net() walks the stale entry, producing a

slab-use-after-free reported by KASAN, followed by a kernel BUG at

net/core/dev.c (LIST_POISON1) in unregister_netdevice_many_notify().

Reachable from an unprivileged user namespace (unshare --user

--map-root-user --net).

ip6gre_changelink() earlier in the same file already uses the cached

t->net; only ip6erspan_changelink() has the wrong shape.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References