Rare overbought condition should trigger a correction.

The CHF has been absolutely smashed against a lot of currencies, notably the "risk on" ones like EUR, GBP, CAD and so on. But also against safe haven currencies like the USD and to a lesser extent, JPY.
Such moves are relatively rare and usually trigger a fairly deep correction.
Fundamentals are bullish mid to long term (risk on + dovish SNB that wants a weaker CHF overall).