You can Sandbox Flash Player in Safari for OS Mavericks as described and explained in this article http://techland.time.com/2013/10/24/finally-you-can-sandbox-flash-player-in-safari-for-os-x-mavericks/
What’s an “app sandbox?. Here’s Apple’s guide to this protection for your security. https://developer.apple.com/library/mac/documentation/Security/Conceptual/AppSandboxDesignGuide/AboutAppSandbox/AboutAppSandbox.html