Well, we have looked over and over and can state that the facts of the hacks of your site does not come from Dolphin side.

Dolphin was checked by "ScanAlert" and has HACKER SAFE® trust mark on one of the sites of our customer I have mentioned about this in the comments before, but did not announce anything about this officially. Since we are arranging some issues with "ScanAlert" about this.

The exploit you have mentioned above was fixed long ago. So, you don't have to see more worry about it. As well we do not get any kinds of security exploits reports in Dolphin for over than half a year.

The first things at which you should firstly look at are the 3d party scripts you have integrated with Dolphin.
We do not know how the integration is performed, we are not responsible for their stability in regards of the security.