In the pjsip channel driver (res_pjsip) in Asterisk 13.x before 13.17.1 and 14.x before 14.6.1, a carefully crafted tel URI in a From, To, or Contact header could cause Asterisk to crash.
https://issues.asterisk.org/jira/browse/ASTERISK-27152
https://bugs.debian.org/873909
http://www.securitytracker.com/id/1039253
http://www.securityfocus.com/bid/100583
http://downloads.asterisk.org/pub/security/AST-2017-007.html