CounterPath X-Lite 3.0 34025, and possibly eyeBeam, allows remote attackers to cause a denial of service (device crash) via a SIP INVITE message without a Content-Type header.
https://www.exploit-db.com/exploits/4285
https://exchange.xforce.ibmcloud.com/vulnerabilities/35975
http://www.securityfocus.com/bid/25299
http://www.securityfocus.com/archive/1/476259/100/100/threaded