CVE-2026-80664 netfilter: xt_nat: reject unsupported target families
A NULL pointer dereference in the Linux kernel netfilter NAT module allows local attackers to cause a system crash via bridge-family rules.
- 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-2026-80664?
CVE-2026-80664 is a high-severity vulnerability in Linux, published on 28 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:
netfilter: xt_nat: reject unsupported target families
xt_nat SNAT and DNAT target handlers assume IP-family conntrack state is present and can dereference a NULL pointer when instantiated from an unsupported family through nft_compat. A bridge-family compat rule can therefore trigger a NULL-dereference in nf_nat_setup_info().
Reject non-IP families in xt_nat_checkentry() so unsupported targets cannot be installed. Keep NFPROTO_INET allowed for valid inet NAT compat users and leave the runtime fast path unchanged.
[ The crash was fixed via 9dbba7e694ec ("netfilter: nft_compat: ebtables emulation must reject non-bridge targets"), so this patch is no longer critical. Nevertheless, NAT is only relevant for ipv4/ipv6, so this extra family check is a good idea in any case. ]
Which versions are affected by CVE-2026-80664?
How do I fix CVE-2026-80664?
Apply the vendor's patch.
Is CVE-2026-80664 being exploited?
There is no known exploitation of CVE-2026-80664 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80664, DEBIAN-CVE-2026-80664, GHSA-4wgj-9qhp-2583, UBUNTU-CVE-2026-80664.