The UPnP IGD implementation in the Pseudo ICS UPnP software on the ZyXEL P-330W allows remote attackers to establish arbitrary port mappings by sending a UPnP AddPortMapping action in a SOAP request to the WAN interface, related to an "external forwarding" vulnerability.

Cross-site request forgery (CSRF) vulnerability in Forms/PortForwarding_Edit_1 on the ZyXEL O2 DSL Router Classic allows remote attackers to hijack the authentication of administrators for requests that insert cross-site scripting (XSS) sequences via the PortRule_Name parameter.

Multiple cross-site request forgery (CSRF) vulnerabilities in the web management interface in the ZyXEL P-330W router allow remote attackers to hijack the authentication of administrators for requests that (1) enable remote router management via goform/formRmtMgt or (2) modify the administrator password via goform/formPasswordSetup.

Cross-site scripting (XSS) vulnerability in the web management interface in the ZyXEL P-330W router allows remote attackers to inject arbitrary web script or HTML via the pingstr parameter and other unspecified vectors.

Cross-site scripting (XSS) vulnerability in ZyXEL ZyWALL 100 allows remote attackers to inject arbitrary web script or HTML via the Referer header, which is not properly handled in a 404 Error page.

ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(PE9) and 3.40(AGD.2) through 3.40(AHQ.3), support authentication over HTTP via a hash string in the hiddenPassword field, which allows remote attackers to obtain access via a replay attack.

ZyXEL Prestige routers have a minimum password length for the admin account that is too small, which makes it easier for remote attackers to guess passwords via brute force methods.

ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), allow remote authenticated users to obtain ISP and Dynamic DNS credentials by sending a direct request for (1) WAN.html, (2) wzPPPOE.html, and (3) rpDyDNS.html, and then reading the HTML source.

ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), have (1) "user" as their default password for the "user" account and (2) "1234" as their default password for the "admin" account, which makes it easier for remote attackers to obtain access.

The SNMP service on ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), has "public" as its default community for both (1) read and (2) write operations, which allows remote attackers to perform administrative actions via SNMP, as demonstrated by reading the Dynamic DNS service password or inserting an XSS sequence into the system.sysName.0 variable, which is displayed on the System Status page.