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.

The Research in Motion BlackBerry 7270 before 4.0 SP1 Bundle 108 does not properly manage transaction states, which allows remote attackers to cause a denial of service (temporary device hang) by sending a certain SIP INVITE message, but not providing an ACK when the call is answered.