Noah, a man of the soil, proceeded to plant a vineyard.  When he drank some of its wine, he became drunk and lay uncovered inside his tent. Ham, the father of Canaan, saw his father’s nakedness and told his two brothers outside. But Shem and Japheth took a garment and laid it across their shoulders; then they walked in backward and covered their father’s nakedness. Their faces were turned the other way so that they would not see their father’s nakedness.
 When Noah awoke from his wine and found out what his youngest son had done to him, he said,
“Cursed be Canaan!
The lowest of slaves
will he be to his brothers.”  Genesis 9:20-25

Noah gets off the ark, plants a vineyard, makes wine and gets drunk (hey, it's been a long couple years).  He lays naked in his tent and his son Canaan walks in and sees him naked.  He goes out and tells his brothers who go into the tent, diverting their eyes, and cover their father up.  Noah hears the news when he wakes up and curses Canaan. 

A little extreme?  Does Noah need anger management?

Canaan disrespected his father.  He should have covered his father up, but he left him that way.

Canaan's attitude expressed to his brothers could have been mocking, making fun of Noah.

We don't know what other incidents preceded this.  It could have been the straw that broke the camel's back (not literally one of the two camels on the ark).  Canaan may have had a history of disrespect and attitude.

So in that case, no it's not extreme.

NOTE: Some think Canaan had sex with his father while he was drunk.  There is no indication in the text that such a thing happened.  The Bible is not shy about such deviant behavior so it would have mentioned it.