setElementTypePrefix(XML_Parser parser, ELEMENT_TYPE *elementType)
{
  DTD * const dtd = parser->m_dtd;  /* save one level of indirection */
  const XML_Char *name;
  for (name = elementType->name; *name; name++) {
    if (*name == XML_T(ASCII_COLON)) {
      PREFIX *prefix;
      const XML_Char *s;
      for (s = elementType->name; s != name; s++) {
        if (!poolAppendChar(&dtd->pool, *s))
          return 0;
      }
      if (!poolAppendChar(&dtd->pool, XML_T('\0')))
        return 0;
      prefix = (PREFIX *)lookup(parser, &dtd->prefixes, poolStart(&dtd->pool),
                                sizeof(PREFIX));
      if (!prefix)
        return 0;
      if (prefix->name == poolStart(&dtd->pool))
        poolFinish(&dtd->pool);
       else
         poolDiscard(&dtd->pool);
       elementType->prefix = prefix;
     }
   }
   return 1;
}

The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.