Possible browser passwords issue

[Goeroeboeroe]

You said something about Android earlier. What I wrote here is only for the desktop. I assume you're using a laptop or desktop computer, because this is a Linux forum.
Because malware can use security holes etc, it's extremely important you only install software from trusted sources. You named FileZilla. If you install FileZilla from some rogue site, it's possible you get more then only FileZilla. But even then you have to give permission, or they're using some kind of bug in the operating system, before something can be uploaded.
I should have made one exception. A browser has access to all files the browser uses. A browser can't upload a file from LibreOffice, without your permission, but in theory a browser can upload the files it uses. Firefox has for example to use the history of visited sites. So in theory Firefox could upload this file.

But that would give a hell of a lot of rumour.
Google Chrome does collect your visited sites, but you can disable that. Google says... I guess Internet Explorer and Edge also collect your visited sites.
But that are still data and files the browser itself uses, it are no data from another application.
I've never heard of a browser uploading the files with passwords. And I'm pretty sure everybody would have heard a lot about that, if a browser ever had done that.

[jglen490]

Sure, it's possible. But, the bad actor has to be operating your machine and have your permissions on the directory and file to get the passwords. Sure, it's possible, but only because the bad actor is able to access your system. Firefox could be a little more proactive with security and provide another protective layer. But no bad guy is getting into that file unless they are actually reading over you shoulder while you have it displayed, or have access to your system using your credentials.

It can be better, but the the sky is falling at a much slower rate than you might think.