Wolves are pretty safe from most other predators because a wolf can kill and prey on most other animals in the wild.
So there's not too many predators of a wolf but still a wolf can and does have a predator that can kill them such as the bear.
A bear that is big enough can usually attack and kill a wolf if they are determined so although wolves are usually safe from being attacked and eaten by other animals the bear if they come into contact with the wolf can sometime win the fight and kill and eat a wolf.
Most times though the bear will want to take on the wolf cub when it comes to preying on them because the wolves baby will be less able to defend itself than the mother or father wolf would be.