It seems the Black Temple is currently easier to get into than intended! A bug is allowing players that haven’t completed the full attunement quest access. Blizzard will be fixing it with the next reset (on September 8th/9th), and those with erroneous access now will lose it.
Some players have noticed that we have a bug associated with the Black Temple attunement questline. With scheduled weekly maintenance next week (September 8 in this region), we’re going to implement a fix for it. The result of that fix will be that the full quest chain to unlock Black Temple will be required for entry, as intended.
At the same time, players who have not completed the attunement quest chain will lose access to Black Temple if they currently have access.
Additionally, if you’re raiding on alts, you’ll need to log-in to a character who has completed the full quest chain in order to unlock the attunement for the rest of your account.
Thank you for your feedback and reports on this!