That would be a problem with the hinting of the font. Overshoots are a natural part of the design, but the hinting code should suppress them at typical sizes (and top and bottom overshoot should kick in at the same time). The fix would be:
1) Make sure you are using the latest version of the font
2) If you are, get somebody who knows from hinting and font rendering to fix it. Contact the designer/developer first. Though of course it is open source, so if you are self-hosting the font, you could just get your version fixed.