In Kamailio before 5.0.7 and 5.1.x before 5.1.4, a crafted SIP message with an invalid Via header causes a segmentation fault and crashes Kamailio. The reason is missing input validation in the crcitt_string_array core function for calculating a CRC hash for To tags. (An additional error is present in the check_via_address core function: this function also misses input validation.) This could result in denial of service and potentially the execution of arbitrary code.
https://www.debian.org/security/2018/dsa-4292
https://skalatan.de/blog/advisory-hw-2018-06
https://lists.debian.org/debian-lts-announce/2018/09/msg00013.html