A vulnerability was found in TOTOLINK A800R 4.1.2cu.5137_B20200730 . It has been rated as critical . Affected is the function setMacQos of the file /cgi-bin/cstecgi.cgi of the component firewall.so . Performing a manipulation of the argument macAddress results in stack-based buffer overflow. This vulnerability is cataloged as CVE-2026-19814 . It is possible to initiate the attack remotely. Furthermore, there is an exploit available.