Secunia

Description

A vulnerability has been identified in Cisco IOS, which can be exploited by malicious people to cause a DoS (Denial of Service) on vulnerable device.

The vulnerability is caused due to an error when processing certain IPv4 traffic. This can be exploited by sending a specially crafted sequence of IPv4 packets to the device, which erroneously may cause the device to set the input queue for the specific interface to full. This results in all further traffic being dropped by the interface.

Successful exploitation requires that processing of IPv4 packets is enabled (default setting).

Solution
Cisco has released updated IOS versions. A patch matrix is available at the web page (in the "Software Versions and Fixes" section) referenced in "Original Advisory".
Further details available in Customer Area

Original Advisory
http://www.cisco.com/warp/public/707/cisco-sa-20030717-blocked.shtml

Deep Links
Links available in Customer Area