A buffer over flow in Xiongmai DVR devices NBD80X16S-KL NBD80X09S-KL NBD80X08S-KL NBD80X09RA-KL AHB80X04R-MH AHB80X04R-MH-V2 AHB80X04-R-MH-V3 AHB80N16T-GS AHB80N32F4-LME and NBD90S0VT-QW allows attackers to cause a Denial of Service (DoS) via a crafted RSTP request.