The OSPFv3 functionality in Cisco IOS XR 5.1 allows remote attackers to cause a denial of service (process crash) via a malformed LSA Type-1 packet, aka Bug ID CSCuj82176.
http://tools.cisco.com/security/center/viewAlert.x?alertId=31675
http://tools.cisco.com/security/center/content/CiscoSecurityNotice/CVE-2013-5565