Chuck McAuley provided Proof-of-Concept code that demonstrates that MFSA 2006-23 was not fixed for all cases. In Firefox 1.5.0.2 it is still possible to pre-fill a text input control with the path to a file at a known location and then change the type of the input control to a file upload control without having the value reset as intended.
Disable JavaScript until you have upgraded to a fixed version.
Vulmon