From one of my usergroups :
Hi All!
[
it.slashdot.org]
Turning off 'Open Safe Files' in the preferences for Safari prevents the widget from automatically installing, but it does still download.
It is a bit conflicting whether it can really attack the system, but as someone said you might get some nasty pop ups or keyloggers.
Let's hope Apple have already seen this and have a patch out soon!
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There isn't a need to worry too much, the nasty widget is a 'proof of concept' file, which means it's been made to prove a security issue, but won't damage your computer or files. Might be a good idea to get your security updates as they come out over the next week and be a bit careful downloading widgets on Safari under Tiger on mission critical machines.