From: Steve G <linux_4ever>

In the png_format_buffer function located in pngerror.c around
line 133 is the following code:

   if (message == NULL)
      buffer[iout] = 0;
   else
   {
      buffer[iout++] = ':';
      buffer[iout++] = ' ';
      png_memcpy(buffer+iout, message, 64);
      buffer[iout+63] = 0;
   }
                                                                     
          
This code is called from the png_chunk_error & png_chunk_warning
functions. An example of their use would be in pngutil.c around
line 119.
                                                                     
          
 png_chunk_error(png_ptr, "CRC error");
                                                                     
          
In the above code, the message being constructed is only 10
characters long. The png_memcpy function will unconditionally
access 54 bytes beyond the message.

This could cause a carefully crafted png image to cause a denial of
service.

Possibly embargoed; marking as embargoed until communicated otherwise.