A stack-based buffer overflow vulnerability (CVE-2026-4213) affects multiple D-Link NAS devices including DNS and DNR series models. The vulnerability is in the cgi_myfavorite_del_user/cgi_myfavorite_verify functions of /cgi-bin/gui_mgr.cgi file. The flaw can be exploited remotely through manipulation and allows attackers to cause buffer overflow. Public exploits are available, making this a high-priority security concern for affected D-Link network storage devices.