Asterisk Open Source 1.0.x and 1.2.x before 1.2.29 and Business Edition A.x.x and B.x.x before B.2.5.3, when pedantic parsing (aka pedanticsipchecking) is enabled, allows remote attackers to cause a denial of service (daemon crash) via a SIP INVITE message that lacks a From header, related to invocations of the ast_uri_decode function, and improper handling of (1) an empty const string and (2) a NULL pointer.
https://www.exploit-db.com/exploits/5749
https://exchange.xforce.ibmcloud.com/vulnerabilities/42823
http://www.vupen.com/english/advisories/2008/1731
http://www.securitytracker.com/id?1020166
http://www.securityfocus.com/archive/1/493020/100/0/threaded
http://svn.digium.com/view/asterisk?view=rev&revision=120109
http://security.gentoo.org/glsa/glsa-200905-01.xml
http://secunia.com/advisories/34982
http://secunia.com/advisories/30517