A vulnerability has been reported in Cisco IOS/CatOS, which can be exploited by malicious people to cause a DoS (Denial of Service).

The vulnerability is caused due to an unspecified error in the handling of VLAN Trunking Protocol (VTP) packets. This can be exploited to crash an affected device by sending a specially crafted packet to a switch interface configured to operate as a trunk port.

Successful exploitation requires that "VTP Operating Mode" is set to "server" or "client".

The vulnerability is reported in Cisco IOS, CatOS, and Cisco IOS with Ethernet Switch Modules for Cisco 1800/2600/2800/3600/3700/3800 Series Routers.

Solution
Apply configuration best practices to limit exposure to exploitation (please see the vendor advisory for details).

Provided and/or discovered by
The vendor credits showrun.lee.

Changelog
Further details available to Secunia VIM customers

Original Advisory
Cisco:
http://www.cisco.com/warp/public/707/cisco-sr-20081105-vtp.shtml

showrun.lee:
http://sh0wrun.blogspot.com/2009/01/dos-code-for-cisco-vlan-trunking.html

Deep Links
Links available to Secunia VIM customers