chan_sip.c in the SIP channel driver in Asterisk Open Source 1.8.x before 1.8.11.1 and 10.x before 10.3.1 and Asterisk Business Edition C.3.x before C.3.7.4, when the trustrpid option is enabled, allows remote authenticated users to cause a denial of service (daemon crash) by sending a SIP UPDATE message that triggers a connected-line update attempt without an associated channel.
Gentoo Linux Security Advisory 201206-5 - Multiple vulnerabilities in Asterisk might allow remote attackers to execute arbitrary code. Versions less than 1.8.12.1 are affected.