Adobe has announced that there is a critical zero day exploit in Adobe Flash, which is affecting Windows, Mac OS X, Linux, Solaris and Android. Adobe havent given very many details about the exploit.
Adobe has only said that the vulernabilility could case a crash or potentially allow a hacker to take control of an affected system, although they have said at the moment that only Flash for Windows is being exploited.
A Security Advisory (APSA10-03) has been posted in regards to a new Adobe Flash Player issue (CVE-2010-2884). A critical vulnerability exists in Adobe Flash Player 10.1.82.76 and earlier versions for Windows, Macintosh, Linux, Solaris and Android. This vulnerability also affects Adobe Reader 9.3.4 for Windows, Macintosh and UNIX, and Adobe Acrobat 9.3.4 and earlier versions for Windows and Macintosh. This vulnerability could cause a crash and potentially allow an attacker to take control of the affected system. There are reports that this vulnerability is being actively exploited in the wild against Flash Player on Windows.
You can see updates on the Adobe website.