The CGI endpoints v2x00.cgi and cgiwcg.cgi of DrayTek Vigor3910 devices through 4.3.2.6 are vulnerable to buffer overflows, by authenticated users, because of missing bounds checking on parameters passed through POST requests to the strncpy function.
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.