CVE-2026-23300 net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop When a standalone IPv6 nexthop object is created with a loopback device e.g., "ip -6 nexthop add id 100 dev lo", fib6nhinit misclassifies it as a reject route...