Microsoft SharePoint Portal Server 2003 SP3 and SharePoint Server 2007 SP3, 2010 SP1 and SP2, and 2013 do not properly process unassigned workflows, which allows remote attackers to cause a denial of service (W3WP process hang) via a crafted URL, aka "SharePoint Denial of Service Vulnerability."
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.