GF_Err elng_Size(GF_Box *s)
{
	GF_ExtendedLanguageBox *ptr = (GF_ExtendedLanguageBox *)s;

	if (ptr->extended_language) {
		ptr->size += strlen(ptr->extended_language)+1;
	}
	return GF_OK;
}

The product reads data past the end, or before the beginning, of the intended buffer.