Here's the old repository we used for the Cataclysm server CATAWOW ( Later changed name to ADVERSEWOW )
Patch is 4.0.6, back in the day (2011-2015) Catawow used to be a pretty populair server with around 100-500 people online.
If you want to explore the core, the link to the repository is uploaded with the full commit history!

This release is for educational purposes, as the source is not used anymore by any server, i feel like it should be public.