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.
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.