Google Home app showing other people's devices that are connected to different networks

[my_precious]

Recently, I got a notifcation on my galaxy note 8 saying a device is casting on your WiFi and it had options to pause / stop it. I had nothing casting on my google home (the only casting device I own) so I was really surprised. I opened my google home app and it was showing 4 devices. When I looked at the details, they were connected to different WiFis (none of them mine) and were owned by someone else. I did not add or link them. I had all the options that are available for my own device - play / pause, reboot, forget / connect WiFi, etc.

I contacted google home support to confirm this. They said only devices that are connected to the same WiFi as my phone are supposed to show up in the app under "Devices". In order to see the details / control them, they need to be added and linked to my account. I have screenshots of the device details that showed up in my app.

Is this a bug with Google Home / android that I am unaware of? If not, is this the right forum to bring this to light? I feel like this is a bug security / privacy concern.

 

[B. Diddy]

Welcome to Android Central! Do you have your own router and wi-fi network, or are you connected to a shared network (like in an apartment or condo)?

 

[my_precious]

I have my own router and wi-fi network that no one else uses. At first I thought maybe some one is using my wi-fi but I went into my router settings and verified no one else is connected to it.
When I checked the settings of these devices, they are all connected to different wi-fi networks.

 

[B. Diddy]

That does sound pretty strange. Send feedback to Google from within the Google Home app's settings menu about it. Make sure to include a screenshot showing all of those other devices and networks.

 

[my_precious]

Yes, I am planning on contacting them about the issue. However, I was wondering how is this possible and if it's something that we need to worry about. What if we start seeing someone else's home security systems, etc. that are connected to google home and can control it too.

Note: I just added the screenshots to the post which I had missed adding earlier.

 

[B. Diddy]

Oh, I think I see the issue. Those devices have Guest Mode turned on: https://support.google.com/chromecast/answer/6109286?hl=en. It allows anyone to cast something to that device without having to log into the wi-fi network. I just noticed that on my own TV. It's more of an issue for the owners of the other devices -- they could theoretically have some random person start casting media on their device as a guest. But as long as you turn off Guest Mode on your devices, they can't do the same to you.

Are the screenshots for the devices where Guest mode is turned off for your devices, or are those also unknown?

 

[my_precious]

All these screenshots are for unknown devices. So even with guest mode turned off for them, I can see them in my google home app.
If the guest mode is turned on for any device, a guest can cast to that device using the cast option in a supported app. However, the guest should not be able to see this device under their google home app right? The problem here is that I can see these people's devices and even control it (turn on / off the guest mode for example).

 

[B. Diddy]

That shouldn't happen. I can't explain it, sorry. If you're on good terms with your neighbors, maybe drop by their place and ask if you can compare devices.