ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), allow remote authenticated users to gain privileges by accessing administrative URIs, as demonstrated by rpSysAdmin.html.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2008-1521)