Security Researchers confirmed, 'Nearly all encrypted traffic, including usernames, passwords, and even Apple app updates can be captured.' with man-in-the-middle attack.
"Apple has never worked with the NSA to create a backdoor in any of our products, including iPhone. Additionally, we have been unaware of this alleged NSA program targeting our products. Whenever we hear about attempts to undermine Apple's industry-leading security, we thoroughly investigate and take appropriate steps to protect our customers. We will continue to use our resources to stay ahead of malicious hackers and defend our customers from security attacks, regardless of who's behind them."
To Check, whether your web browser is vulnerable to SSL flaw, Click here and to be safe, you are recommended to use an alternate web browser, rather than Safari web browser and avoid using public and unsecured networks.
UPDATE: Apple has finally today releases Mac OS X 10.9.2, which includes a fix for a major SSL security flaw and bringing with it a number of "improvements to the stability, compatibility and security of your Mac."