CVE-2026-72250 netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag

In the Linux kernel, the following vulnerability has been resolved: netfilter: nfconntrackreasm: guard macheader adjustment after IPv6 defrag nfctfrag6reasm slides the packet head forward to drop the IPv6 fragment header and then unconditionally advances skb-macheader: skb-macheader += sizeofstru...