Multiple vulnerabilities were fixed in the latest version of asterisk.

AST-2017-002: Buffer Overrun in PJSIP transaction layer

A remote crash can be triggered by sending a SIP packet to Asterisk with a specially crafted CSeq header and a Via header with no branch parameter. The issue is that the PJSIP RFC 2543 transaction key generation algorithm does not allocate a large enough buffer. By overrunning the buffer, the memory allocation table becomes corrupted, leading to an eventual crash.

http://downloads.asterisk.org/pub/security/AST-2017-002.html

AST-2017-003: Crash in PJSIP multi-part body parser

The multi-part body parser in PJSIP contains a logical error that can make certain multi-part body parts attempt to read memory from outside the allowed boundaries. A specially-crafted packet can trigger these invalid reads and potentially induce a crash.

http://downloads.asterisk.org/pub/security/AST-2017-003.html

AST-2017-004: Memory exhaustion on short SCCP packets

A remote memory exhaustion can be triggered by sending an SCCP packet to Asterisk system with “chan_skinny” enabled that is larger than the length of the SCCP header but smaller than the packet length specified in the header. The loop that reads the rest of the packet doesn’t detect that the call to read() returned end-of-file before the expected number of bytes and continues infinitely. The “partial data” message logging in that tight loop causes Asterisk to exhaust all available memory.

http://downloads.asterisk.org/pub/security/AST-2017-004.html