I assume you mean you have one fork not two with the same problem. Some forks have replaceable steerer which can be pressed through the bottom of the crown, others don't. If yours isn't a replaceable steerer model you're SOL. If it is, It should be tight, as it's a press fit. You might want to show it to a skilled mechanic to locate the exact problem, and it might be repairable.

As to urgency, there is none as long as you don't ride the bike (winter here in NY, so there's time). But it's definitely unsafe if loose. The steerer to crown junction is probably the most critical on a bike, and it doesn't take much imagination to see the consequences of a failure there.