CVE-2026-46120 ip6_gre: Use cached t->net in ip6erspan_changelink().
A use-after-free in the Linux kernel's ip6erspan_changelink function allows local attackers to cause a system crash or potentially escalate privileges.
- 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-2026-46120?
CVE-2026-46120 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 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:
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-46120?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46120?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-46120 being exploited?
There is no known exploitation of CVE-2026-46120 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-88887, BELL-CVE-2026-46120, DEBIAN-CVE-2026-46120, GHSA-92hv-jcvf-rqg6, ROOT-OS-DEBIAN-11-CVE-2026-46120, ROOT-OS-DEBIAN-12-CVE-2026-46120 and 3 more.