It only shows up on light hair colors, not the darker ones...can this be fixed?
Screen shot:
http://privat.bahnhof.se/wb220832/TEMP/hairglow.png
Are using any lighting mods since I find those alter the lighting effects or an ENB/Reshade it looks like you do. I think that is showing the background lighting effect on the character which you do not see if using the vanilla lighting or at least not as much. I think you can disable it in the ini file.
I will see if I can find the line you need to edit or add.
[edit]
This might help you.
http://www.nexusmods.com/fallout4/mods/3771/?