Cisco Security Advisory – Several features within Cisco IOS Software are affected by a crafted UDP packet vulnerability. If any of the affected features are enabled, a successful attack will result in a blocked input queue on the inbound interface. Only crafted UDP packets destined for the device could result in the interface being blocked, transit traffic will not block the interface.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/76066/cisco-sa-20090325-udp.txt
Source: https://packetstormsecurity.com/files/76066/Cisco-Security-Advisory-20090325-udp.html