Multiple syscalls in the compat subsystem for NetBSD before 2.0 allow local users to cause a denial of service (kernel crash) via a large signal number to (1) xxx_sys_kill, (2) xxx_sys_sigaction, and possibly other translation functions.
TCP, when using a large Window Size, makes it easier for remote attackers to guess sequence numbers and cause a denial of service (connection loss) to persistent TCP connections by repeatedly injecting a TCP RST packet, especially in protocols that use long-lived connections, such as BGP.