CVE-2026-98379netfilter: ip6t_rpfilter: reject routes without inet6_dev

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_rpfilter: reject routes without inet6_dev ip6_route_lookup() can return an error-free route whose rt6i_idev is NULL. Lowering an external nexthop device's MTU below IPV6_MIN_MTU tears down its inet6_dev while fib6_ifdown() leaves routes using nexthop objects in the FIB. An unprivileged user can construct this state with rtnetlink in a private user and network namespace, then trigger a NULL dereference through an IPv6 rpfilter lookup: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000 KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: rpfilter_mt (net/ipv6/netfilter/ip6t_rpfilter.c:75) Call Trace: ip6t_do_table (net/ipv6/netfilter/ip6_tables.c:316) nf_hook_slow (net/netfilter/core.c:619) ipv6_rcv (net/ipv6/ip6_input.c:351) __netif_receive_skb_one_core (net/core/dev.c:6216) process_backlog (net/core/dev.c:6680) __napi_poll (net/core/dev.c:7739) net_rx_action (net/core/dev.c:7959) handle_softirqs (kernel/softirq.c:622) do_softirq.part.0 (kernel/softirq.c:523) __local_bh_enable_ip (kernel/softirq.c:450) __dev_queue_xmit (net/core/dev.c:4913) packet_sendmsg (net/packet/af_packet.c:3139) __sys_sendto (net/socket.c:2252) __x64_sys_sendto (net/socket.c:2259) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Kernel panic - not syncing: Fatal exception in interrupt Reject routes without an inet6_dev immediately after lookup. Such routes are not eligible for reverse-path filtering, and the check protects all later rt6i_idev dereferences.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/f4de78756b0fddbd125b2b1b77c74f2eccc8e977
• https://git.kernel.org/stable/c/1681ab6dd1271f2f36047490793b78b1848bbcc9
• https://git.kernel.org/stable/c/65487e9e99431ffcf05024a817f51ee4e3bd9b47
• https://git.kernel.org/stable/c/f49da48bd679cfee646d6a40dd02b1933de577d1
• https://git.kernel.org/stable/c/290c96e5d9471d1ded9ab1e8ffbb04f6ee7b0f40
• https://git.kernel.org/stable/c/eafe081ea77d25b5c8e601680671b4ecb4520e7d
• https://git.kernel.org/stable/c/3a7384bc2e66217c9a01a392281334f4423740a0
• https://git.kernel.org/stable/c/1b9b5323725e458906c7620a3bc10398b51ad954