Hello,
You should not work under "Absolute Maximum Ratings".
The MCU is not made to work in these conditions, just not explode.
The MCU is made to work within the operating conditions, which should be 5V +/-10%.
If you go higher on an input, you will inject current, that is bad practise and there is a limit (also in the databook) after which the device will be destroyed also.
So, during operating conditions, it's not 6V or 7V, but Supply Voltage +/- 0.5V (a diode threshold voltage).
Alban.