Computer systems around the world are vulnerable to attack after Microsoft issued a patch to fix a security flaw.

The flaw, which was discovered by Google researchers, affects all versions of Microsoft Windows operating system and could allow hackers to take control of a computer.

Microsoft issued a patch for the flaw on Tuesday, but many computer systems may not have been updated yet, leaving them vulnerable to attack.

“This is a big deal. This is the kind of vulnerability that a lot of attackers are going to be interested in,” said Adrienne Hall, Microsoft’s general manager for Trustworthy Computing.…