The router model DR300 from Shenzhen Kangda Xin Intelligent Network Technology includes default telnet services on both WAN and LAN interfaces and hardcoded login credentials. These weaknesses allow an attacker who gains access to the telnet service to read and write the router’s memory, overwrite firmware stored in flash, and inspect active network connections and connected devices, effectively enabling remote firmware modification and extensive system control.

Vendor Shenzhen Kangda Xin Intelligent Network Technology Co., Ltd. product DR300, specifically version 2.1.2.121.

Because the credentials are fixed and telnet is enabled by default, remote exploitation is straightforward once the network is reachable. The CVSS score of 9.8 highlights the criticality of this vulnerability. The vulnerability is likely to be widely exploitable via the internet, but no EPSS score is currently available and the vulnerability is not listed in the CISA KEV catalog. Attackers would target the telnet service over the WAN or LAN interfaces to achieve unauthorized read/write access, which could lead to permanent firmware compromise or persistent remote code execution.