CVE-2026-72442 netfilter: flowtable: fix and simplify IP6IP6 tunnel handling
A missing header pull in Linux kernel netfilter flowtable IP6IP6 tunnel handling can cause a null pointer dereference, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72442?
CVE-2026-72442 is a critical vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfilter: flowtable: fix and simplify IP6IP6 tunnel handling
Fix nf_flow_ip6_tunnel_proto() to use pskb_may_pull() instead of skb_header_pointer() to ensure the outer IPv6 header is in the skb headroom, which is required for subsequent packet processing. Move ctx->offset update inside the IPPROTO_IPV6 conditional block since it should only be adjusted when an IP6IP6 tunnel is actually detected. Simplify the rx path by removing ipv6_skip_exthdr() and checking ip6h->nexthdr directly, as the flowtable fast path only handles simple IP6IP6 encapsulation without extension headers. Drop the tunnel encapsulation limit destination option support from the tx path to match, since the rx path no longer handles extension headers. Remove the encap_limit parameter from nf_flow_offload_ipv6_forward(), nf_flow_tunnel_ip6ip6_push() and nf_flow_tunnel_v6_push(), along with the ipv6_tel_txoption struct and related headroom/MTU adjustments.
Which versions are affected by CVE-2026-72442?
How do I fix CVE-2026-72442?
Apply the vendor's patch.
Is CVE-2026-72442 being exploited?
There is no known exploitation of CVE-2026-72442 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-72442, GHSA-wphh-fr34-rp9q, UBUNTU-CVE-2026-72442.