Although the consumer edition of Microsoft Vista has yet to be on the market, computer security companies are already finding flaws in the operating system.

The OS may not be as secure as Microsoft is hoping it will be. According to a report in the New York Times, a computer security researcher has said it's possible to increase user privileges on Vista, while another firm said it found five flaws, including one in IE7 that makes it possible for a system to be infected with malware by visiting a rigged site.

Computer security software developers at Determina said that they had found four more flaws, including one that compromises the Microsoft Exchange mail server by sending it an infected email.

The same newspaper report said that one analyst trawling through online discussion forums had found an offer of $50,000 for information about flaws in Vista.

Meanwhile Microsoft promises that Vista is its most secure and stable OS to date.