ImageMagick Has Heap Out-of-Bounds Read in DCM Decoder (ReadDCMImage)

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 7.1.2-15 and 6.9.13-40, a heap out-of-bounds read vulnerability exists in the `coders/dcm.c` module. When processing DICOM files with a specific configuration, the decoder loop incorrectly reads bytes per iteration. This causes the function to read past the end of the allocated buffer, potentially leading to a Denial of Service (crash) or Information Disclosure (leaking heap memory into the image). Versions 7.1.2-15 and 6.9.13-40 contain a patch.