File stealing by changing input type


Claus Jørgensen reports that a text input box can be pre-filled with a
filename  and then turned into a file-upload control with the contents
intact, allowing a malicious website the ability to steal any local file
whose name they can guess.

Jesse Ruderman reports a variation, changing the type of the input control
in an event handler to work around some of the initial checks.

Workaround

Upgrade to fixed version.

References

[1]https://bugzilla.mozilla.org/show_bug.cgi?id=325947
[2]https://bugzilla.mozilla.org/show_bug.cgi?id=328566


This issue also affects FC4