An issue was discovered on the Grandstream HT801 Analog Telephone Adaptor before 1.0.29.8. From the limited configuration shell, it is possible to set the malicious gdbdebugserver variable. As a result, after a reboot, the device downloads and executes malicious scripts from an attacker-defined host.

Multiple buffer overflows in the limited configuration shell (/sbin/gsconfig) on Grandstream HT801 devices before 1.0.29 allow remote authenticated users to execute arbitrary code as root via a crafted manageif setting, thus bypassing the intended restrictions of this shell and taking full control of the device. There are default weak credentials that can be used to authenticate.

Grandstream HT800 series firmware version 1.0.17.5 and below contain a backdoor in the SSH service. An authenticated remote attacker can obtain a root shell by correctly answering a challenge prompt.

Grandstream HT800 series firmware version 1.0.17.5 and below is vulnerable to a denial of service attack against the TR-069 service. An unauthenticated remote attacker can stop the service due to a NULL pointer dereference in the TR-069 service. This condition is triggered due to mishandling of the HTTP Authentication field.

Grandstream HT800 series firmware version 1.0.17.5 and below is vulnerable to CPU exhaustion due to an infinite loop in the TR-069 service. Unauthenticated remote attackers can trigger this case by sending a one character TCP message to the TR-069 service.

Grandstream HT800 series firmware version 1.0.17.5 and below is vulnerable to an OS command injection vulnerability. Unauthenticated remote attackers can execute arbitrary commands as root by crafting a special configuration file and sending a crafted SIP message.