Plug-ins may be used to seed the system clipboard with paths to a target file, while the user may not expect that to be the contents of the clipboard. If the user can be convinced to focus a file input and paste the contents of the clipboard, the file can then be immediately uploaded without requiring the user’s confirmation.
Opera Software has released Opera 10.60, where file inputs no longer allow the user to paste file paths without interaction. To paste or type file paths, users must now use the “Choose” button, and type or paste into the file chooser provided by the operating system.
Thanks to Andrew Valums for reporting this issue to Opera Software.