Niels Provos Systrace 1.6f and earlier on the x8664 Linux platform allows local users to bypass intended access restrictions by making a 32-bit syscall with a syscall number that corresponds to a policy-compliant 64-bit syscall, related to race conditions that occur in monitoring 64-bit processes.
The systraceexit function in the systrace utility for NetBSD-current and 2.0 before April 16, 2004, and certain FreeBSD ports, does not verify the owner of the /dec/systrace connection before setting euid to 0, which allows local users to gain root privileges.