An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. By sending a signal to the CLI process, undocumented functionality is triggered. Specifically, a menu can be triggered by sending the SIGQUIT signal to the CLI application (e.g., through CTRL+\ via SSH). The access control check for this menu does work and prohibits accessing the menu, which contains "Password recovery for specific user" options. The menu is believed to be accessible using a serial console.
The management portal on ZyXEL PMG5318-B20A devices with firmware 1.00AANC0b5 does not terminate sessions upon a logout action, which allows remote attackers to bypass intended access restrictions by leveraging an unattended workstation.
Belkin F9K1102 2 devices with firmware 2.10.17 use an improper algorithm for selecting the ID value in the header of a DNS query, which makes it easier for remote attackers to spoof responses by predicting this value.
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 CloudCNM SecuManager 3.1.0 and 3.1.1 has no authentication for /cnr requests.
Zyxel CloudCNM SecuManager 3.1.0 and 3.1.1 has no authentication for /registerCpe requests.