A stack buffer overflow vulnerability exists in the ToToLink LR1200GB (V9.1.0u.6619_B20230130) and NR1800X (V9.1.0u.6681_B20230703) Router firmware within the cstecgi.cgi binary (setDefResponse function). The binary reads the "IpAddress" parameter from a web request and copies it into a fixed-size stack buffer using strcpy() without any length validation. Maliciously crafted input can overflow the buffer, leading to potential arbitrary code execution or memory corruption, without requiring authentication.