There are no undiscovered quests.

Blizzard had stated a few years ago that there was one (and only one) quest that had never been found. I never heard any announcement saying that someone had finally found it.

I remember hearing this as well, a GM (?) claimed that four (IIRC) quests had never been discovered.

"There are no undiscovered quests."

... or at least none that we've found ;-)

/duck

I can speak definitively on this one because I was the GM that everyone mistakenly quoted. :)

Someone asked me if there were any undiscovered quests and I made a little trivia thread out of it with four questions. People read the questions and assumed they had something to do with "lost" quests. They didn't.

Quest information is stored in files that are easily accessible in builds of the game client. That's how Wowhead and MMO-C (and we) datamine that kind of info. Any and all quests are stored that way. If there were any quests no one had found yet, they would have to not even be contained in the game files with the rest of the quests, which, as you know, is pretty much impossible!