CVE-2026-23381

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled<br /> <br /> When booting with the &amp;#39;ipv6.disable=1&amp;#39; parameter, the nd_tbl is never<br /> initialized because inet6_init() exits before ndisc_init() is called<br /> which initializes it. Then, if neigh_suppress is enabled and an ICMPv6<br /> Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will<br /> dereference ipv6_stub-&gt;nd_tbl which is NULL, passing it to<br /> neigh_lookup(). This causes a kernel NULL pointer dereference.<br /> <br /> BUG: kernel NULL pointer dereference, address: 0000000000000268<br /> Oops: 0000 [#1] PREEMPT SMP NOPTI<br /> [...]<br /> RIP: 0010:neigh_lookup+0x16/0xe0<br /> [...]<br /> Call Trace:<br /> <br /> ? neigh_lookup+0x16/0xe0<br /> br_do_suppress_nd+0x160/0x290 [bridge]<br /> br_handle_frame_finish+0x500/0x620 [bridge]<br /> br_handle_frame+0x353/0x440 [bridge]<br /> __netif_receive_skb_core.constprop.0+0x298/0x1110<br /> __netif_receive_skb_one_core+0x3d/0xa0<br /> process_backlog+0xa0/0x140<br /> __napi_poll+0x2c/0x170<br /> net_rx_action+0x2c4/0x3a0<br /> handle_softirqs+0xd0/0x270<br /> do_softirq+0x3f/0x60<br /> <br /> Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in<br /> the callers. This is in essence disabling NS/NA suppression when IPv6 is<br /> disabled.