Can one android app read another app's temp files?

Question

Android

There is a common directory in android, in my opinion /phone
All applications write temporary files there, when you delete the application, the data from it remains there if the developer did not take care to delete them.
There are questions:
1) by design the system does not delete these temporary files from this directory?
2) android does not know which files belong to which application?
3) Can one application read another application's data from this directory, then this is a security hole?

Answer 1

In Android, each application runs as a separate Unix user, and has the rights of that user. A system of users and groups is used to separate rights. /data is quite clearly separated by rights - without root rights, applications do not even see what files are there.

Answer 2

I read temporary files from the directory of a popular messenger, and there the photos that were sent to me are in unencrypted form, my device is not rooted.

Where are these files located? If they are in an arbitrary directory on a partition that is in fat32, then shared access cannot be applied to them. Therefore, it is necessary to clarify what exactly you mean by "temporary files"

Answer 3

3) Why is this a security hole when it comes to the public memory section? Look at the Android documentation developer.android.com/intl/ru/guide/topics/data/da...
To be honest, I'm surprised that such material is published in the Information Security section, when in fact everything is said in the documentation.