libheif before 1.19.6 has a NULL pointer dereference in ImageItem_Grid::get_decoder in image-items/grid.cc because a grid image can reference a nonexistent image item.
Buffer overflow vulnerability in function convert_colorspace in heif_colorconversion.cc in libheif v1.6.2, allows attackers to cause a denial of service and disclose sensitive information, via a crafted HEIF file.