Code exploiting the universal XSS, or cross-site scripting, bug “is being exploited in the wild in active targeted attacks designed to trick the user into clicking on a malicious link delivered in an email message,”
The Flash vulnerability affects versions 10.3.183.7 and earlier for Windows, Mac, Linux, and Solaris and Flash 10.3.186.6 for Google's Android operating system for mobile phones. Those using recent versions of Flash on Windows or Mac OS X can install the upgrade automatically after being prompted by an auto-update mechanism.
More at: http://www.theregister.co.uk/2011/09/21/emergency_adobe_flash_update/
Adobe Security Bulletin: