The last info from their irc channel is that the site's admins decided to migrate to an entirely new tracker framework with fewer security issues.

Update:

From Staff member:

This is exactly the case. We are migrating everything over to a more secure platform, but currently though we are limited on devs and limited on free time to be able to work on this.

We might be gone awhile but we (staff) all have agreed to try our best to make sure UGC doesn't die completely.

First we are working on the backend and making sure everything is tip top, and then we will be (hopefully) migrating over all user data and tables, and then it's a bit of housekeeping and tweeking.

If you would like to keep up to date on what is happening you can join our IRC as I will be posting updates when we reach milestones in the migration process.

Cheers.

Nice news, hope it goes well