How do you see light? Most basement walls (particularly ext. walls are cosmetic anyway). The upper floor is supported by the bearing walls and the foundation walls. If it is a weight bearing wall, such as in the middle of the room. Then you need to worry. If not it really is not a problem. Is is finished (drywalled) or unfinished? Once it is finished with drywall and baseboard it should cover it???? Is the wall solid?? Can you move it??