I can concur these issues exist in several other models as well. In fact, on any UPnP enabled D-Link from 868L and down, merely selecting "Display Hidden Elements" inside the developer tool bar, will expose the entire administrative GUI.
Additional models I found the same bug, though I'm so sure that the latest firmware completely fixes the issues.
Wireless AC1200 Dual Band Gigabit Cloud Router DIR-850L
Wireless AC1200 Dual Band Gigabit Cloud Router DIR-860L
Wireless N150 Home Router DIR-601
Wireless N 8-Port Router DIR-632