Linksys EtherFast BEFN2PS4, BEFSR41, and BEFSR81 Routers, and possibly other products, allow remote attackers to gain sensitive information and cause a denial of service via an SNMP query for the default community string "public," which causes the router to change its configuration and send SNMP trap information back to the system that initiated the query.
http://www.securityfocus.com/bid/3797
http://www.securityfocus.com/bid/3795