Right in the heart of tax-filing season, the Canada Revenue Agency (CRA) shut down access to online tax services on Wednesday because of an Internet bug that has made data on many of the world’s major websites vulnerable to theft by hackers. “We have received information concerning an Internet security vulnerability named the Heartbleed Bug,” the CRA, the government’s tax collector, said. The tax filing deadline in Canada is April 30, 15 days later than in the United States, but the CRA said it would give consideration to taxpayers unable to comply with their filing requirements because of the service interruption.