This happened the first time, but this is very serious. The icon on the system panel shows active VPN, the widget shows an active VPN, and the connection editor shows an active VPN connection as well. Although in the very same time dnsleaktest, speedtest, or any other IP checker shows my physical IP, in any browser.

I attached a screenshot which clarifies the situation. I'm in Hungary, and  was connected to a Sweden VPN. Once, I don't know when I lost the VPN tunnel, and browsed further without it. I didn't notice it until I checked intentionally. There was no notification, and the icon stayed the same (the lock is still there).

This is a very serious issue.

Reproducible: Didn't try

Steps to Reproduce:
1. Connect to VPN.
2. Browse, do computer stuff.
3. Wait for the act of God.

Actual Results:  
The whole plasma-nm shows you are still connected to VPN, although you aren't.

Expected Results:  
plasma-nm MUST show the real current status always.
(Although this doesn't relate to the bug, but plasma-nm should take VPN more seriously. There should be an option to force VPN, and stop every connection if the tunnel ceases.)

I'm using Kubuntu 15.04.
I always keep an eye on my IP, and this is the first time I experienced this issue. Sad thing I was expecting this to happen on time, that's why I keep checking my IP regularly.
But again, this is a very serious issue. Such a thing just should not happen.