Bug discovered on latest release - Endermen can deal damage to players without a clear line of sight by attacking through the exposed edges of two blocks placed diagonally from each other.

Steps to Reproduce:

[Step 1]Agro (make hostile) any Enderman in survival mode.
[Step 2]Step under a ceiling two blocks tall 
[Step 3]Place blocks in a "cross" formation with the player at the center, making sure not to "fill in" the corners. The pattern is similar to the movement of a "King" piece in Chess.

Observed Results:

Aggressive Enderman will remain hostile and hurt player through the solid block - the "range" of the Enderman attack does not check for line of sight with the target.

Expected Results:

Aggressive Enderman should remain hostile, but should be unable to harm the player unless they can physically reach the player through legal means.

Notes:

Found the bug playing on a Hardcore world. Was mining in a Cave when accidentally looked at Enderman. Died.