Dirk Mueller reported an off by one buffer overflow flaw in the way QT parses certain unicode strings.
To quote Dirk:
Ive found a off-by-one buffer overflow in QUtf8Decoder::toUnicode(). It is not exploitable with Qt 4.x or above because there is an additional QChar(0) being allocated in QString, however it is still a bug there, as the array returned by utf16() etc is no longer terminated properly.