CINCINNATI - All five voting systems used in Ohio, where electoral votes narrowly swung two elections toward President Bush, have critical flaws that could undermine the integrity of the 2008 general election, a report commissioned by the state's top elections official has found.

At polling stations, teams working on the study were able to pick locks to access memory cards and use hand-held devices to plug false vote counts into machines. At boards of election, they were able to introduce malignant software into servers.

"It was worse than I anticipated," the official, Secretary of State Jennifer Brunner, said of the report.

Brunner proposed replacing all of the state's voting machines. She wants all counties to use optical scan machines that read and electronically record paper ballots that are filled in manually by voters.

She called for legislation and financing to be in place by April so the new machines can be used in the presidential election next November. She said she could not estimate the cost of the changes.

Florida, another swing state with a history of voting problems, is also scrapping touch-screen machines and switching to optical scan ones for the election. Such systems have gained favor because experts say they are more reliable than others.

Brunner, a Democrat, succeeded J. Kenneth Blackwell, a Republican who came under fire for simultaneously overseeing the 2004 election and serving as co-chairman of President Bush's re-election campaign in Ohio.

She ordered the study as part of a pledge to overhaul voting after problems made headlines for hours-long lines in the 2000 and 2004 elections and a scandal in Cuyahoga County, which includes Cleveland, that led to the convictions of two elections workers on charges of rigging recounts.

The study released Friday found that voting machines and central servers made by Elections Systems & Software; Premier Election Solutions, formerly Diebold; and Hart InterCivic, were easily corrupted.

Chris Riggall, a Premier spokesman, said hardware and software problems have been corrected in his company's new products, which will be available for installation in 2008.

"It is important to note," he said, "that there has not been a single documented case of a successful attack against an electronic voting system, in Ohio or anywhere in the United States."