The Collaborative International Dictionary of English v.0.48:

Riddle \Rid"dle\, v. t. [imp. & p. p. Riddled (r[i^]d"d'ld);
   p. pr. & vb. n. Riddling (r[i^]d"dl[i^]ng).]
   1. To separate, as grain from the chaff, with a riddle; to
      pass through a riddle; as, riddle wheat; to riddle coal or
      gravel.
      [1913 Webster]

   2. To perforate so as to make like a riddle; to make many
      holes in; as, a house riddled with shot.
      [1913 Webster]

WordNet (r) 3.0 (2006):

riddled
    adj 1: (often followed by `with') damaged throughout by numerous
           perforations or holes; "a sweater riddled with moth
           holes"; "cliffs riddled with caves"; "the bullet-riddled
           target"
    2: spread throughout; "cities riddled with corruption"