Cistron RADIUS daemon (radiusd-cistron) 1.6.6 and earlier allows remote attackers to cause a denial of service and possibly execute arbitrary code via a large value in an NAS-Port attribute, which is interpreted as a negative number and causes a buffer overflow.
http://www.turbolinux.com/security/TLSA-2003-40.txt
http://www.novell.com/linux/security/advisories/2003_030_radiusd_cistron.html
http://www.debian.org/security/2003/dsa-321
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000664