Board Thread:General Discussion/@comment-32090487-20180413054458/@comment-2A02:C7F:963F:BA00:8535:6A69:3C8A:2443-20180416125555

Tupka217 wrote: It did not fork an old version; it forked the most recent version at the time. There are no full version upgrades of MediaWiki. But elements of newer versions are implemented. Including security.

If you have concerns over FANDOM's security, send it to Special:Contact/feedback. They'll tell you the exact same things that have been mentioned above. Don't worry about it. Any new features, bug fixes and security flaws that was come with newer versions won't get backported into Fandom's version of MediaWiki.

So Fandom did forked MediaWiki back in 2012 and FANDOM says there are no more version upgrades.