That's why I don't use any KeePass extensions. I just don't trust browser enough to be able to get any of my passwords.
I'm thinking about writing my own extension which will communicate with KeePass in a way that suits me (basically: when I'm pressing button in browser, it'll popup KeePass window with search field filled with server domain. Then I can either auto-type password from KeePass or copy it to clipboard, either way I'm only using KeePass and browser extension have no way to get any information.