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Mozilla Foundation Security Advisory 2006-23

Title: File stealing by changing input type
Impact: High
Date: April 13, 2006
Reporter: Claus Jörgensen
Products: Firefox, Mozilla Suite

Fixed in: Firefox
  Firefox 1.0.8
  SeaMonkey 1.0.1
  Mozilla Suite 1.7.13


Claus Jörgensen 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.


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