HOUSTON (AP) — A security researcher disclosed a gaping security hole at the outfit that manages Georgia's election technology, days before the state holds a closely watched congressional runoff vote on June 20.

The security failure left the state's 6.7 million voter records and other sensitive files exposed to hackers, and may have been left unpatched for seven months. The revealed files might have allowed attackers to plant malware and possibly rig votes or wreak chaos with voter rolls during elections.

Georgia is especially vulnerable to such disruption, as the entire state relies on antiqu...