MitraStar GPT-2541GNAC (HGU) 1.00(VNJ0)b1 and DSL-100HN-T1 ES_113WJY0b16 devices have a zyad1234 password for the zyad1234 account, which is equivalent to root and undocumented.

MitraStar GPT-2541GNAC (HGU) 1.00(VNJ0)b1 and DSL-100HN-T1 ES_113WJY0b16 devices allow remote authenticated users to obtain root access by specifying /bin/sh as the command to execute.

Multiple cross-site scripting (XSS) vulnerabilities in Forms/rpAuth_1 on ZyXEL P-660HW-T1 2 devices with ZyNOS firmware 3.40(AXH.0) allow remote attackers to inject arbitrary web script or HTML via the (1) LoginPassword or (2) hiddenPassword parameter.

The TCP implementation in (1) Linux, (2) platforms based on BSD Unix, (3) Microsoft Windows, (4) Cisco products, and probably other operating systems allows remote attackers to cause a denial of service (connection queue exhaustion) via multiple vectors that manipulate information in the TCP state table, as demonstrated by sockstress.

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), do not use a salt when calculating an MD5 password hash, which makes it easier for attackers to crack passwords.