Security problem

That is not a security problem as anyone opening your iPhone camera does not involve them accessing your personal data at all, the most someone can do is take photos for you. When it comes to accessing your photo content, that requires a passcode or biometrics and is not accessible by anyone.

It is not a security problem as photos cannot be accesed

Camera is accessible, yes. Your photos are not.

"Security problem: Anyone can access camera on lock screen sliding from right to left...what security providing apple to customer ????"

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Camera Being Accessible:

Yes. But, there are cases that have a flip that can go over the camera cover. Potentially, it's for keeping a clear camera, but it will also block if from being used, when you don't want it to see anything. Or you can purchase a plastic one. Many of these, you can find on Amazon: iphone camera cover case