A vulnerability was found in TOTOLINK A800R 4.1.2cu.5137_B20200730 . It has been declared as critical . This impacts the function setMacFilterRules of the file /cgi-bin/cstecgi.cgi of the component firewall.so . Such manipulation of the argument Comment leads to stack-based buffer overflow. This vulnerability is listed as CVE-2026-19813 . The attack may be performed from remote. In addition, an exploit is available.