An issue was discovered in D-Link DIR-806 devices. There is a stack-based buffer overflow in function hnap_main at /htdocs/cgibin. The function will call sprintf without checking the length of strings in parameters given by HTTP header and can be controlled by users. And it finally leads to a stack-based buffer overflow via a special HTTP header.

hnap_main in /htdocs/cgibin on D-link DIR-806 v1.0 devices has a stack-based buffer overflow via a long HTTP header that has "SOAPAction: http://purenetworks.com/HNAP1/GetDeviceSettings/" at the beginning.