p1003_1b.c in FreeBSD 6.1 allows local users to cause an unspecified denial of service by setting a scheduler policy, which should only be settable by root.
http://www.securityfocus.com/bid/20517
http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/posix4/p1003_1b.c.diff?r1=1.24&r2=1.24.2.1
http://secunia.com/advisories/22413
http://lists.freebsd.org/pipermail/cvs-src/2006-May/063969.html