This vulnerability exists in the D-Link DIR-878A1 router firmware FW101B04.bin within the 'SetDynamicDNSSettings' functionality. The 'ServerAddress' and 'Hostname' parameters submitted via prog.cgi are stored in NVRAM and subsequently used by the rc script to construct system commands executed through the twsystem() function. Due to insufficient input validation, an unauthenticated remote attacker can send a specially crafted HTTP request to inject arbitrary commands, leading to command execution on the device. The CVSS 3.1 base score is 6.5 with vector AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N, reflecting network attack vector, low attack complexity, no privileges or user interaction required, and limited confidentiality and integrity impact without availability impact.

An unauthenticated remote attacker can execute arbitrary system commands on the affected D-Link DIR-878A1 router by exploiting the command injection vulnerability in the Dynamic DNS settings. This can lead to partial confidentiality and integrity compromise of the device. There is no indication of availability impact. No known exploits are reported in the wild at this time.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the router's management interface from untrusted networks to reduce exposure. Monitor vendor communications for updates on patches or mitigations.