A buffer overflow vulnerability in the CGI program in the Zyxel GS1900-48 switch firmware version V2.80(AAHN.1)C0 and earlier could allow an authenticated, LAN-based attacker with administrator privileges to cause denial of service (DoS) conditions via a crafted URL.

A post-authentication command injection vulnerability in the CGI program in the Zyxel GS1900-48 switch firmware version V2.80(AAHN.1)C0 and earlier could allow an authenticated, LAN-based attacker with administrator privileges to execute some operating system (OS) commands on an affected device by sending a crafted HTTP request.

An insufficient entropy vulnerability caused by the improper use of a randomness function with low entropy for web authentication tokens generation exists in the Zyxel GS1900-10HP firmware version V2.80(AAZI.0)C0. This vulnerability could allow a LAN-based attacker a slight chance to gain a valid session token if multiple authenticated sessions are alive.

The improper privilege management vulnerability in the Zyxel GS1900-24EP switch firmware version V2.70(ABTO.5) could allow an authenticated local user with read-only access to modify system settings on a vulnerable device.

The privilege escalation vulnerability in the Zyxel GS1900-8 firmware version V2.70(AAHH.3) and the GS1900-8HP firmware version V2.70(AAHI.3) could allow an authenticated, local attacker with administrator privileges to execute some system commands as 'root' on a vulnerable device via SSH.

An insufficient entropy vulnerability caused by the improper use of randomness sources with low entropy for RSA key pair generation was found in Zyxel GS1900 series firmware versions prior to V2.70. This vulnerability could allow an unauthenticated attacker to retrieve a private key by factoring the RSA modulus N in the certificate of the web administration interface.

A vulnerability in the 'libsal.so' of the Zyxel GS1900 series firmware version 2.60 could allow an authenticated local user to execute arbitrary OS commands via a crafted function call.

A vulnerability in the TFTP client of Zyxel GS1900 series firmware, XGS1210 series firmware, and XGS1250 series firmware, which could allow an authenticated LAN user to execute arbitrary OS commands via the GUI of the vulnerable device.

A vulnerability was found in the CGI program in Zyxel GS1900-8 firmware version V2.60, that did not properly sterilize packet contents and could allow an authenticated, local user to perform a cross-site scripting (XSS) attack via a crafted LLDP packet.

An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. User accounts created through the web interface of the device, when given non-admin level privileges, have the same level of privileged access as administrators when connecting to the device via SSH (while their permissions via the web interface are in fact restricted). This allows normal users to obtain the administrative password by running the tech-support command via the CLI: this contains the encrypted passwords for all users on the device. As these passwords are encrypted using well-known and static parameters, they can be decrypted and the original passwords (including the administrator password) can be obtained.