So there's a bug in something, either the writer or the reader, or both.
The QXmlWriter does not escape VT (vertical tab)http://www.fileformat.info/info/unicode/char/000b/index.htm which a user has managed to put into QPlainTextEdit which I then save out to XML.

The QXmlReader then fails to read the element. I encoded it in a CDATA section and it STILL fails to parse it.

I have attached the simplest XML file ever which you'll see fails to fully parse. I have worked around this by simply sanitising my output by doing .replace(QChar(0x000B), ' '); (since we don't particularly care for it) but it seems like borking out when it's in the CDATA section is bad - it's not supposed to be parsed by the parser.