The asynchronous I/O facility in 4.4 BSD kernel does not check user credentials when setting the recipient of I/O notification, which allows local users to cause a denial of service by using certain ioctl and fcntl calls to cause the signal to be sent to an arbitrary process ID.
spaceball program in SpaceWare 7.3 v1.0 in IRIX 6.2 allows local users to gain root privileges by setting the HOSTNAME environmental variable to contain the commands to be executed.