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

The vulnerability is caused due to an error in the DNS implementation during the decompression of compressed DNS messages and can be exploited via a specially crafted DNS packet containing invalid information in the compressed section.

Successful exploitation crashes a vulnerable device or causes it to function abnormally.

The vulnerability affects the following products:
* Cisco IP Phones 7902/7905/7912
* Cisco ATA (Analog Telephone Adaptor) 186/188
* Cisco Unity Express

The following Cisco ACNS (Application and Content Networking System) devices are also affected:
* Cisco 500 Series Content Engines
* Cisco 7300 Series Content Engines
* Cisco Content Routers 4400 series
* Cisco Content Distribution Manager 4600 series
* Cisco Content Engine Module for Cisco 2600, 2800, 3600, 3700, and 3800 series Integrated Service Routers.

Solution
See patch matrix in vendor advisory for information about fixes.
Further details available to Secunia VIM customers

Provided and/or discovered by
NISCC credits Dr. Steve Beaty.

Changelog
Further details available to Secunia VIM customers

Original Advisory
Cisco:
http://www.cisco.com/warp/public/707/cisco-sn-20050524-dns.shtml

NISCC:
http://www.niscc.gov.uk/niscc/docs/al-20050524-00433.html

Deep Links
Links available to Secunia VIM customers