Diode letting voltage through in circuit simulator - bug or real?
Look at the current in the diode. It's a measly 170nA. Take a look at the diode curve below. Even when reverse biased some current will leak through. This is what you are seeing. The problem is the 10Meg can't source much current so the leakage vs the current in the resistor balance to 6.7V on the floating node. Change your resistor to 10k and you see what you would expect since the resistor can now source much more current and drown out the leakage of the diode to keep the floating node biased to 5V. Change it to 100 GigaOhm and then the resistor can't source any current and the diode leakage will bias the floating node to 12V.

 


Source