The Internet Group Management Protocol (IGMP) allows local users to cause a denial of service via an IGMP membership report to a target's Ethernet address instead of the Multicast group address, which causes the target to stop sending reports to the router and effectively disconnect the group from the network.
cpio on FreeBSD 2.1.0, Debian GNU/Linux 3.0, and possibly other operating systems, uses a 0 umask when creating files using the -O (archive) or -F options, which creates the files with mode 0666 and allows local users to read or overwrite those files.