Apple yesterday posted a new support document and sent an email to its security mailing list noting that it is now requiring all OS X users to upgrade to the latest version of the Adobe Flash Player plug-in for Safari to address potential security vulnerabilities.
The company is blocking all older versions Adobe Flash Player prior to 16.0.0.305, and users with an out-of-date version of the plug-in will see messages like "Blocked plug-in" or "Flash out-of-date" when attempting to view Flash content within Safari before updating to the newest version.
The 16.0.0.305 and 13.0.0.269 updates were released by Adobe on February 5 to fix a zero-day vulnerability that was being exploited by hackers against Windows machines.APPLE-SA-2015-02-05-1 OS X: Flash Player plug-in blocked
Due to security issues in older versions, Apple has updated the web plug-in blocking mechanism to disable all versions prior to Flash Player 16.0.0.305 and 13.0.0.269.
Article Link: Apple Forces Users to Upgrade to Newest Adobe Flash Player to Patch Vulnerabilities