Fellow Windows users have probably had the same experience I’ve had when it comes to Mac owners — listening to them claim that unlike Windows, their systems are impervious to assault.

For years I’ve been telling them they’re wrong, and they rarely listen. But now I have hard evidence.

If there were any doubt that the Mac is far from a fortress, the recent release of an Apple patch fixing 13 security flaws in OS X should put them to rest.

Among the security holes is one that would allow an attacker to remotely execute malicious code, and take over someone’s system. There’s also a spoofing flaw and a way to knock down SSL protection to a less-secure version, among others.

Need more evidence that the Mac is vulnerable? The SANS Institute has listed Mac security flaws among its list of top 20 security issues. The institute notes “Although Mac OS X has security features implemented out of the box…the user still faces many vulnerabilities.”

There’s no doubt that right now the Mac is more secure than the PC. But Vista includes a more hardened operating system, and more security features, and by the time it comes out, I wouldn’t bet that the Mac will be more secure.

As for now…if you’re a Mac user, it’s time to get used to the security patching process.

What do you think about Mac security?