In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix ndtbl NULL dereference when IPv6 is disabled When booting with the 'ipv6.disable=1' parameter, the ndtbl is never initialized because inet6init() exits before ndiscinit() is called which initializes it. Then, if neighsuppress is enabled and an ICMPv6 Neighbor Discovery packet reaches the bridge, brdosuppressnd() will dereference ipv6stub->ndtbl which is NULL, passing it to neighlookup(). This causes a kernel NULL pointer dereference. BUG: kernel NULL pointer dereference, address: 0000000000000268 Oops: 0000 [#1] PREEMPT SMP NOPTI [...] RIP: 0010:neighlookup+0x16/0xe0 [...] Call Trace: <IRQ> ? neighlookup+0x16/0xe0 brdosuppressnd+0x160/0x290 [bridge] brhandleframefinish+0x500/0x620 [bridge] brhandle_frame+0x353/0x440 [bridge] __netifreceiveskb_core.constprop.0+0x298/0x1110 __netifreceiveskbonecore+0x3d/0xa0 process_backlog+0xa0/0x140 __napipoll+0x2c/0x170 netrxaction+0x2c4/0x3a0 handlesoftirqs+0xd0/0x270 dosoftirq+0x3f/0x60 Fix this by replacing ISENABLED(IPV6) call with ipv6modenabled() in the callers. This is in essence disabling NS/NA suppression when IPv6 is disabled.