A vulnerability was found in TOTOLINK A800R 4.1.2cu.5137_B20200730 and classified as critical . The impacted element is the function setIpQosRules of the file /cgi-bin/cstecgi.cgi of the component firewall.so . The manipulation of the argument Comment results in stack-based buffer overflow. This vulnerability is identified as CVE-2026-19811 . The attack can be executed remotely. Additionally, an exploit exists.