Security Focus warns that an old bug in Firefox and Internet Explorer is still unfixed:
The design flaws, which resemble issues found in June 2006 and as far back as 2000, allow certain keystrokes to be sent to a different application as long as the attacker can convince the user to type the appropriate characters. Attackers could use typing-intensive tasks such as keyboard-based games, captchas and comment fields to collect a user's input and send the appropriate keystrokes to a hidden application.
"The vulnerability allows the attacker to silently redirect focus of selected key press events to an otherwise protected file upload form field," researcher Michal Zalewski, who discovered the most recent issues, stated in a post to the Full Disclosure security mailing list on Sunday. "This is possible because of how onKeyDown (and) onKeyPress events are handled, allowing the focus to be moved between the two. If exploited, this enables the attacker to read arbitrary files on victim's system."
The issue appears to affect versions 1.5 and 2.0 of Mozilla's Firefox browser and versions 5.0, 5.5, 6 and 7 of Microsoft's Internet Explorer.