source: http://www.securityfocus.com/bid/26001/info

Cisco IOS is prone to a remote buffer-overflow vulnerability in its LPD service because it fails to perform adequate boundary checks on user-supplied data.

Attackers can exploit this issue to execute arbitrary code in the context of the affected component. Attackers could also restart the device, resulting in denial-of-service conditions.

To exploit this issue, an attacker must be able to change the hostname of affected routers. SNMP write access may allow attackers to change the router's hostname.

Versions prior to Cisco IOS 12.2(18)SXF11, 12.4(16a), and 12.4(2)T6 are vulnerable.

This issue is being tracked by Cisco bug ID CSCsj86725.

NOTE: This issue is related to the vulnerabilities described in BID 25994 (Cisco IOS Multiple Unspecified Stack Overflow Vulnerabilities). 

The following command is sufficient to demonstrate changing the hostname of affected devices via SNMP:

snmpset -Os -c private -v 1 10.0.0.1 system.sysName.0 s long_hostname

When the hostname has been changed, issue the following command to demonstrate this issue to crash affected devices:

telnet 10.0.0.1 515