The Diebold GEMS central tabulator contains a stunning security hole.

[CVX]

Issue: Manipulation technique found in the Diebold central tabulator -- 1,000 of these systems are in place, and they count up to two million votes at a time.

By entering a 2-digit code in a hidden location, a second set of votes is created. This set of votes can be changed, so that it no longer matches the correct votes. The voting system will then read the totals from the bogus vote set. It takes only seconds to change the votes, and to date not a single location in the U.S. has implemented security measures to fully mitigate the risks.

More:

http://www.blackboxvoting.org/?q=node/view/78