I can confirm that this happened. Have been using CCleaner for more than five-six years and I haven't changed the settings. I knew it was something to do with CCleaner as I noticed that the history is lost after a clean up (I have been keeping the same settings for a while - say an year at least). But haven't updated CCleaner recently. Firefox - yes. So I feel there is something CCleaner needs to check with the recent Firefox update I believe.
edit: I didn't lose any bookmarks. Only the history (I keep my bookmarks in Chrome). Firefox is my safe place where I had a couple of years' history saved and important passwords.
