A white-hat hacker from Sweden says he's found a "serious" security hole in Mac OS X Yosemite that could allow an attacker to take control of your Mac, reports Macworld UK (http://tinyurl.com/m5etd52).

Emil Kvarnhammar, a hacker at Swedish security firm Truesec, calls the vulnerability "rootpipe." He says it's a "privilege escalation vulnerability," which means that even without a password an attacker could gain the highest level of access on a machine, known as root access. From there, the attacker has full control of the system.

Apple hasn't fixed the flaw yet, Kvarnhammar says, so Truesec won't provide details of how it works.