My Macbook kernel panics and force-reboots itself because of a bug in some newer Firefox browser feature(s) which are used by a JS-based GBA emulator which was trending on HN yesterday. I can consistently duplicate the kernel panic by resizing the browser window while the emulator is running. I've never in my life experienced such a catastrophic bug from a Flash demo.
At worst, such a devastating bug has a decent chance of harboring its own RCE which has yet to be discovered or disclosed; at best, it's one of the most extreme local DOS attacks that a webpage could possibly launch against a client.
Just because it's much more trendy to bash Adobe than it is to bash Firefox doesn't mean that Firefox's problems are nonexistent.