I just read this question which made me discover the funny anecdote of The Head of Vecna (Note that apart from the hand and eye artifacts in the DMG, I had never heard of Vecna before).
Therefore I start reading a bit about this Vecna character, and learn that he became a god of secrets.
Now I'm currently preparing to run the Curse of Strahd adventure, and this started ringing a bell in my mind (Warning : CoS spoilers):
The Amber Temple was dedicated to a god of secrets, and its main hall contains a statue that represents "a faceless god of secrets" (translated from French) The parallel is strong, especially since the Head of Vecna story talks about the thirst for power destroying the adventurers...
Is there any official source that links this CoS element with the Head of Vecna anecdote or am I just linking two unrelated stories ?