Format string vulnerability on the Research in Motion BlackBerry 7270 before 4.0 SP1 Bundle 108 allows remote attackers to cause a denial of service (blocked call reception and calling) via format string specifiers in an SIP INVITE message that lacks a host name in the Contact header.
https://exchange.xforce.ibmcloud.com/vulnerabilities/35077
http://www.sipera.com/index.php?action=resources%2Cthreat_advisory&tid=208&
http://www.kb.cert.org/vuls/id/619465
http://www.blackberry.com/btsc/articles/218/KB12707_f.SAL_Public.html