The tcp_cwnd_reduction function in net/ipv4/tcp_input.c in the Linux kernel before 4.3.5 allows remote attackers to cause a denial of service (divide-by-zero error and system crash) via crafted TCP traffic.
https://github.com/torvalds/linux/commit/8b8a321ff72c785ed5e8b4cf6eda20b35d427390
https://bugzilla.redhat.com/show_bug.cgi?id=1302219
http://www.openwall.com/lists/oss-security/2016/01/25/5