Buffer overflow in the RPC library (lib/rpc/rpc_dtablesize.c) used by libgssrpc and kadmind in MIT Kerberos 5 (krb5) 1.2.2, and probably other versions before 1.3, when running on systems whose unistd.h does not define the FD_SETSIZE macro, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code by triggering a large number of open file descriptors.