In GraphicsMagick from version 1.3.8 to 1.4 snapshot-20190403 Q8, there is a heap-based buffer overflow in the function WritePDBImage of coders/pdb.c, which allows an attacker to cause a denial of service or possibly have unspecified other impact via a crafted image file. This is related to MagickBitStreamMSBWrite in magick/bit_stream.c.