TL;DR:
Serials beginning with XAW1:
XAW1007XXX and below are safe to buy
XAW1008XXX not safe to buy, probably patched
XAW1009XXX and above definitely patched
Serials beginning with XAW4:
No patched Switch has been reported yet
Serials beginning with XAW7:
XAW70017X and below are safe to buy
XAW70018X not safe to buy, probably patched
XAW70019X and above definitely patched
Serials beginning with XAJ1:
No patched Switch has been reported yet
Serials beginning with XAJ4:
XAJ40052X and below are safe to buy
XAJ40053X not safe to buy, probably patched
XAJ4006XX and above definitely patched
Serials beginning with XAJ7:
XAJ70042X and below are safe to buy
XAJ70043X not safe to buy, probably patched
XAJ7005XX and above definitely patched