A heap-based buffer over-read in H5Z__filter_scaleoffset() in src/H5Zscaleoffset.c in HDF5 through 2.2.0 lets an attacker cause a denial of service (application crash) with a crafted HDF5 file. When the stored minimum bits equal the full precision of the datatype, the decoder copies d_nelmts * size bytes from the compressed chunk without checking that the chunk holds that many bytes. Both values come from attacker-controlled scale-offset filter parameters in the dataset's filter pipeline message.