Per
NVD, the issue is describes as:
TCP, when using a large Window Size, makes it easier for remote attackers to guess sequence numbers and cause a denial of service (connection loss) to persistent TCP connections by repeatedly injecting a TCP SYN or RST packet, especially in protocols that use long-lived connections, such as BGP.
Additional details and analysis of this vulnerability can be found in:
http://lwn.net/Articles/81560/