A certain Red Hat patch to the sctp_sock_migrate function in net/sctp/socket.c in the Linux kernel before 2.6.21, as used in Red Hat Enterprise Linux (RHEL) 5, allows remote attackers to cause a denial of service (NULL pointer dereference and OOPS) via a crafted SCTP packet.
https://github.com/torvalds/linux/commit/ea2bc483ff5caada7c4aa0d5fbf87d3a6590273d
http://www.openwall.com/lists/oss-security/2011/08/30/1