The Linksys WRT54G router allows remote attackers to cause a denial of service (device restart) via a long username and password to the FTP interface.
https://exchange.xforce.ibmcloud.com/vulnerabilities/41127
http://www.securityfocus.com/archive/1/489009/100/0/threaded
http://www.gnucitizen.org/projects/router-hacking-challenge/