The Linux kernel 2.6.20 through 2.6.21.1 allows remote attackers to cause a denial of service (panic) via a certain IPv6 packet, possibly involving the Jumbo Payload hop-by-hop option (jumbogram).
https://www.exploit-db.com/exploits/4893
https://exchange.xforce.ibmcloud.com/vulnerabilities/39643
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.21.2