HarfBuzz before 1.0.4 allows remote attackers to cause a denial of service (invalid read of two bytes and application crash) because of GPOS and GSUB table mishandling, related to hb-ot-layout-gpos-table.hh, hb-ot-layout-gsub-table.hh, and hb-ot-layout-gsubgpos-private.hh.