Mariusz Mlynski reported that if you could convince a user to hold down the Enter key--as part of a game or test, perhaps--a malicious page could pop up a download dialog where the held key would then activate the default Open action. For some file types this would be merely annoying (the equivalent of a pop-up) but other file types have powerful scripting capabilities. And this would provide an avenue for an attacker to exploit a vulnerability in applications not normally exposed to potentially hostile internet content.
Mariusz also reported a similar flaw with manual plugin installation
using the PLUGINSPAGE attribute. It was possible to create
an internal error that suppressed a confirmation dialog, such that holding
enter would lead to the installation of an arbitrary add-on. (This variant
did not affect Firefox 3.6)
Vulmon