A stack-based buffer overflow vulnerability exists in the httpd binary of Linksys E1200 v2 routers running firmware version E1200_v2.0.11.001_us.tar.gz. The vulnerability arises from unsafe use of sprintf in the apply_cgi and block_cgi functions when processing the "url" CGI parameter, allowing remote attackers to trigger a buffer overflow. This can lead to arbitrary code execution or denial of service without requiring authentication.