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.

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.

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.

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.

The default SNMP configuration on ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), has a Trusted Host value of 0.0.0.0, which allows remote attackers to send SNMP requests from any source IP address.

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, 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 authentication data by making direct HTTP requests and then reading the HTML source, as demonstrated by a request for (1) RemMagSNMP.html, which discloses SNMP communities; or (2) WLAN.html, which discloses WEP keys.

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 650R-31 router running ZyNOS FW v3.40(KO.1) allows remote attackers to cause a denial of service (CPU consumption and network loss) via crafted fragmented IP packets.

Zyxel P2000W Version 1 VOIP WIFI Phone Wj.00.10 allows remote attackers to obtain sensitive information and possibly cause a denial of service via a direct connection to UDP port 9090, which is undocumented and does not require authentication.

ZyXEL Prestige 642R and 642R-I routers do not filter the routers' Telnet and FTP ports on the external WAN interface from inside access, allowing someone on an internal computer to reconfigure the router, if the password is known.

Cross-site scripting (XSS) vulnerability in the Forms/rpSysAdmin script on the Zyxel Prestige 660H-61 ADSL Router running firmware 3.40(PT.0)b32 allows remote attackers to inject arbitrary web script or HTML via hex-encoded values in the a parameter.

Zyxel P2000W Version 1 VOIP WIFI Phone Wj.00.10 uses hardcoded IP addresses for its DNS servers, which could allow remote attackers to cause a denial of service or hijack Zyxel phones by attacking or spoofing the hardcoded DNS servers. NOTE: it could be argued that this issue reflects an inherent limitation of DNS itself, so perhaps it should not be included in CVE.

Zyxel Prestige 681 and 1600 SDSL Routers allow remote attackers to cause a denial of service via malformed packets with (1) an IP length less than actual packet size, or (2) fragmented packets whose size exceeds 64 kilobytes after reassembly.

ZyXEL Prestige 642R allows remote attackers to cause a denial of service in the Telnet, FTP, and DHCP services (crash) via a TCP packet with both the SYN and ACK flags set.

ZyXEL Prestige 642R 2.50(FA.1) and Prestige 310 V3.25(M.01), allows remote attackers to cause a denial of service via an oversized, fragmented "jolt" style ICMP packet.

Prestige 650HW-31 running Rompager 4.7 software allows remote attackers to cause a denial of service (device reboot) via a long password.

ZyXEL Prestige 623, 650, and 652 HW Routers, and possibly other versions, with HTTP Remote Administration enabled, does not require a password to access rpFWUpload.html, which allows remote attackers to reset the router configuration file.

Zyxel P681 running ZyNOS Vt020225a contains portions of memory in an ARP request, which allows remote attackers to obtain sensitive information by sniffing the network.

Zyxel P310, P314, P324 and Netgear RT311, RT314 running the latest firmware, allows remote attackers on the WAN to obtain the IP address of the LAN side interface by pinging a valid LAN IP address, which generates an ARP reply from the WAN address side that maps the LAN IP address to the WAN's MAC address.