Cribs that were made before September 1986 or without a label are not safe for use. http://www.hc-sc.gc.ca/cps-spc/pubs/...enfants_e.html
Jelle, with a crib, when in doubt - throw it out. The space between the slats can not be more than 2 3/8" and no cut outs on the head or foot boards. Mold is usually green or black - if it's red it might be the original stain of the wood coming through. You wouldn't want to use that crib because even if you paint over it you will feel like hell if, in the future, a baby chews on a bar or the head or foot boards and a paint chip comes off and they get something much more dangerous in their mouths.