The web configuration interface for Catalyst 3500 XL switches allows remote attackers to execute arbitrary commands without authentication when the enable password is not set, via a URL containing the /exec/ directory.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5415
http://www.securityfocus.com/bid/1846
http://archives.neohapsis.com/archives/bugtraq/2000-11/0194.html
http://archives.neohapsis.com/archives/bugtraq/2000-10/0380.html