An issue was discovered on Tenda AC7 V15.03.06.44_CN, AC9 V15.03.05.19(6318)_CN, AC10 V15.03.06.23_CN, AC15 V15.03.05.19_CN, and AC18 V15.03.05.19(6318)_CN devices. There is a buffer overflow vulnerability in the router's web server -- httpd. While processing the 'ntpServer' parameter for a post request, the value is directly used in a strcpy to a local variable placed on the stack, which overrides the return address of the function.