The JPEGLSCodec::DecodeExtent function in MediaStorageAndFileFormat/gdcmJPEGLSCodec.cxx in Grassroots DICOM (aka GDCM) before 2.6.2 allows remote attackers to obtain sensitive information from process memory or cause a denial of service (application crash) via an embedded JPEG-LS image with dimensions larger than the selected region in a (1) two-dimensional or (2) three-dimensional DICOM image file, which triggers an out-of-bounds read.