Are there any items in game which give permanent boost to certain skills or skill groups (combat magic stealth) ?

There was an item that did that in Oblivion and Morrowind, is it back in Skyrim?

There is a ring that boosts smithing and a amulet that gives a boost to magic health and stamana

there are lots

I have heard a rumour that this certain artifact is glitched in Skyrim, and is abused by many players

Yes, many items will boost your abilities as long as you wear them. The boost isn't permanent in the sense that if you have a ring which gives you a boost, removal of the ring removes to boost as well, but the objects don't 'wear out' either. You put them back on and they work as before.