Asterisk Open Source 1.2.26 through 1.2.30.3 and Business Edition B.2.3.5 through B.2.5.5, when realtime IAX2 users are enabled, allows remote attackers to cause a denial of service (crash) via authentication attempts involving (1) an unknown user or (2) a user using hostname matching.
downloads.digium.com/pub/security/AST-2008-012.html
osvdb.org/50675
secunia.com/advisories/32956
secunia.com/advisories/34982
security.gentoo.org/glsa/glsa-200905-01.xml
securityreason.com/securityalert/4769
www.securityfocus.com/archive/1/499117/100/0/threaded
www.securityfocus.com/bid/32773
www.securitytracker.com/id?1021378
www.vupen.com/english/advisories/2008/3403