Unspecified vulnerability in Cisco IOS 12.0 through 12.4 allows remote attackers to execute arbitrary code via a malformed SIP packet, aka CSCsi80749.
http://secunia.com/advisories/26363
http://securitytracker.com/id?1018533
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5075
http://www.cisco.com/en/US/products/products_security_advisory09186a0080899653.shtml