static Image *ReadMONOImage(const ImageInfo *image_info,
  ExceptionInfo *exception)
{
  Image
    *image;

  MagickBooleanType
    status;

  register IndexPacket
    *indexes;

  register PixelPacket
    *q;

  register ssize_t
    x;

  size_t
    bit,
    byte;

  ssize_t
    y;

  /*
    Open image file.
  */
  assert(image_info != (const ImageInfo *) NULL);
  assert(image_info->signature == MagickSignature);
  if (image_info->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
      image_info->filename);
  assert(exception != (ExceptionInfo *) NULL);
  assert(exception->signature == MagickSignature);
  image=AcquireImage(image_info);
  if ((image->columns == 0) || (image->rows == 0))
    ThrowReaderException(OptionError,"MustSpecifyImageSize");
  status=OpenBlob(image_info,image,ReadBinaryBlobMode,exception);
  if (status == MagickFalse)
    {
      image=DestroyImageList(image);
      return((Image *) NULL);
    }
  if (DiscardBlobBytes(image,image->offset) == MagickFalse)
    ThrowFileException(exception,CorruptImageError,"UnexpectedEndOfFile",
      image->filename);
  /*
    Initialize image colormap.
  */
  image->depth=1;
  if (AcquireImageColormap(image,2) == MagickFalse)
    ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
  if (image_info->ping != MagickFalse)
    {
       (void) CloseBlob(image);
       return(GetFirstImageInList(image));
     }
  status=SetImageExtent(image,image->columns,image->rows);
  if (status == MagickFalse)
    {
      InheritException(exception,&image->exception);
      return(DestroyImageList(image));
    }
   /*
     Convert bi-level image to pixel packets.
   */
  for (y=0; y < (ssize_t) image->rows; y++)
  {
    q=QueueAuthenticPixels(image,0,y,image->columns,1,exception);
    if (q == (PixelPacket *) NULL)
      break;
    indexes=GetAuthenticIndexQueue(image);
    bit=0;
    byte=0;
    for (x=0; x < (ssize_t) image->columns; x++)
    {
      if (bit == 0)
        byte=(size_t) ReadBlobByte(image);
      if (image_info->endian == LSBEndian)
        SetPixelIndex(indexes+x,((byte & 0x01) != 0) ? 0x00 : 0x01)
      else
        SetPixelIndex(indexes+x,((byte & 0x01) != 0) ? 0x01 : 0x00)
      bit++;
      if (bit == 8)
        bit=0;
      byte>>=1;
    }
    if (SyncAuthenticPixels(image,exception) == MagickFalse)
      break;
    status=SetImageProgress(image,LoadImageTag,(MagickOffsetType) y,
      image->rows);
    if (status == MagickFalse)
      break;
  }
  (void) SyncImage(image);
  if (EOFBlob(image) != MagickFalse)
    ThrowFileException(exception,CorruptImageError,"UnexpectedEndOfFile",
      image->filename);
  (void) CloseBlob(image);
  return(GetFirstImageInList(image));
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.