Netpbm before 10.86.51, 11.x before 11.02.30, and 11.03 before 11.15.08 contains a heap buffer overflow in xpmtoppm caused by an unvalidated characters-per-pixel value in the XPM header. Attackers can supply a crafted XPM file with characters-per-pixel greater than 3 to overrun fixed 3-byte colorName hash entries, causing crashes or potentially code execution.