Adobe has posted an announcement about critical vulnerabilities in the Adobe Flash Player for all platforms. Adobe recommends updating to version 18.104.22.168.
Users can determine which version is installed by visiting Adobeis Website. The version is shown inside a box near the top of that page. Or, one can look in: /Library/Internet Plug-ins/ (in Mac OS X) and do a Get Info on the Flash Player.
The latest version of the Flash plug-in for Intel and PPC Macs is also linked from the above Adobe page.