Stack-based buffer overflow in the DtbClsLogin function in NovaStor NovaNET 12 allows remote attackers to (1) execute arbitrary code on Linux platforms via a long username field during backup domain authentication, related to libnnlindtb.so; or (2) cause a denial of service (daemon crash) on Windows platforms via a long username field during backup domain authentication, related to nnwindtb.dll. NOTE: some of these details are obtained from third party information.