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.