Netpbm before 10.86.51, 11.x before 11.02.29, and 11.03 before 11.15.07 contains a heap-based buffer overflow in sgitopnm's readChannels() function when processing RLE-compressed SGI images. Attackers can supply crafted SGI files with oversized offset table lengths to write controlled data past the heap buffer, causing crashes or potential code execution.