  We show that the claimed confirmed planet Kepler-452b (a.k.a. K07016.01, KIC
8311864) can not be confirmed using a purely statistical validation approach.
Kepler detects many more periodic signals from instrumental effects than it
does from transits, and it is likely impossible to confidently distinguish the
two types of event at low signal-to-noise. As a result, the scenario that the
observed signal is due to an instrumental artifact can't be ruled out with 99\%
confidence, and the system must still be considered a candidate planet. We
discuss the implications for other confirmed planets in or near the habitable
zone.
