In Short: flaw found in Symantec antivirus software

Versions of Symantec Corp's anti-virus business security software contain a flaw that could put millions of computers at risk of a crippling worm attack, Internet experts warned on May 26.
Researchers at eEye Digital Security discovered the vulnerability, which they said could allow an attacker to create a worm able to take over a user's computer and destroy critical programs and files.
They rated the threat as high because a hacker could exploit the flaw to get on a machine and edit, remove and delete programs and files without a user doing anything, such as clicking on a link, eEye spokesman Mike Puterbaugh said.
A worm is a computer virus that spreads by sending copies of itself over a network. Most viruses these days are worms, since almost all computers are now linked by networks.