DrayTek Vigor 2960 firmware versions prior to 1.5.1.4 contain an OS command injection vulnerability in the CGI login handler that allows unauthenticated remote attackers to execute arbitrary commands by injecting shell metacharacters into the formpassword parameter. Attackers can exploit unsanitized input passed to the otp_check.sh script to achieve remote code execution with web server privileges. Exploitation requires knowledge of a valid username and that the target account has MOTP authentication enabled.