Steps to reproduce:

1. Open the attached project
2. Open and run 'PasswordInputFieldScene' scene
3. Enter text into the password field
4. Select all of the contents of the password field
5. Copy the selection (Control+C on Windows; Command+C on Mac)
6. Set the focus to the Standard InputField
7. Paste the selection
8. Observe the masked text copies from the password InputField

Note: Same behavior on both Player and Editor. The text can also be pasted in any text field outside of Unity.